Category Archives: Modeling

CFD With Analytical Modeling Gives ATS Edge

In January, Advanced Thermal Solutions, Inc. (ATS) and engineering simulation software leader Future Facilities announced that ATS had purchased multiple seats of 6SigmaET, an electronics thermal simulation software, adding to its CFD (computational fluid dynamics) capabilities.

CFD

ATS engineers are now using 6SigmaET to perform CFD on electronics cooling applications to find optimized thermal solutions for customers. (Advanced Thermal Solutions, Inc.)

In a joint press release from the two companies, ATS founder and CEO Dr. Kaveh Azar said, “We have decades of experience with a broad base of commercially available CFD tools. For the electronics thermal management analyses, 6SigmaET showed excellent agreement with our empirical and analytical modelling.

He added, “We were equally impressed with its ease of use and a short learning curve. Our engineering team was able to apply the tool to different levels of simulation extending from component to system level modelling. The speed of convergence and ease of use of 6SigmaET, have made it the first CFD software to use.”

6SigmaET becomes the lead thermal simulation software for ATS engineers dealing with standard electronics cooling challenges. ATS engineers will be able to quickly and efficiently simulate junction and ambient temperatures across boards and components or define airflow to find fan operating points or get a better understanding of pressure drop in a system.

Dr. Azar continued, “We always want to be working with the best breed of tools to deliver the innovative, high-quality and cost-effective thermal management and packaging solutions our customers expect. As a result, this addition is good news for our customers. The rich features of the 6SigmaET thermal simulation package not only enable us to do more when it comes to simulation, but also allows us to further deliver the solution to our clients in a shorter time interval. It is my highest compliment to 6SigmaET development team for putting together such a robust and effective software.”

Adding 6SigmaET to ATS CFD capabilities, which also includes FloTHERM from Mentor and Autodesk CFD (formerly CFdesign), enables engineers to save customers time in the design phase and makes it easier for ATS engineers to devise optimal thermal solutions.

ATS engineer Anatoly Pikovsky said, “Visual is definitely a great thing to have. If you look at this temperature map, for instance, you can look at the defined map and say right away, okay I have a very high temperature right in the middle.”

Pikovsky, who was working on Autodesk CFD to design a customized cold plate for a customer, demonstrated how the software allows for him to analyze the pattern of fluid flow through complex geometries that were imported from SolidWorks drawings. He used the software to show hot spots and fluid velocity and how small changes, such as the number of fins within the cold plate, could alter the results.

Field Application Engineer Vineet Barot explained that he used 6SigmaET on a board in which there was pressure drop coming from vents at the end of the board. In simulations, he was able to add fins to the heat sink without altering the fan operating point and quickly provide a thermal solution that was presented to a customer. He said, “If you had a standard 1-U chassis you can build it from scratch and run it in half an hour.”

While CFD continues to evolve to handle more complex problems, while also becoming easier to use for engineers, simulations are only part of the solution.

ATS engineers also perform analytical modeling, literally putting pen to paper with basic thermodynamic equations, to define the problem and provide a reference point for simulations. Coupling analytical and computer modeling is what sets ATS apart from its competitors because it ensures that thermal solutions provided by CFD are correct.

“CFD will give you a solution, whether it’s right or wrong, it will give you a solution,” Pikovsky said. “That’s the way it’s designed. Analytical coupled with CFD gives you a good reference point to know whether you’re in the ballpark.”

Analytical modeling also speeds up the process of finding an optimized solution. Rather than spending days or weeks plugging in different fin numbers and heights or trying numerous heat sink geometries, ATS engineers can define a small range of iterations, limiting the variables for CFD, to avoid countless simulations, each of which could take hours to run.

Pikovsky said, “Maybe you’ve designed a heat sink for certain airflow and you want to determine the number of fins. You can do it with CFD, but you start varying fins and it’s going to take you days. Analytical is great because you can determine the optimal number of fins and start CFD with that.”

CFD is a critical component of ATS thermal consulting and design services. 6SigmaET has quickly been adopted by ATS engineers as the lead software and been used in the design of thermal solutions for a number of customers in the past few months.

But, it is the combination of CFD with ATS engineers’ emphasis on analytical modeling that has made ATS a leader in the thermal management of electronics.

For more information about Advanced Thermal Solutions, Inc. (ATS) thermal management consulting and design services, visit https://www.qats.com/consulting or contact ATS at 781.769.2800 or ats-hq@qats.com.

Discussion of Thermal Solution for Stratix 10 FPGA

An Advanced Thermal Solutions, Inc. (ATS) client was planning on upgrading an existing board by adding Altera’s high-powered Stratix 10 FPGAs, with estimates of as many as 90 watts of power being dissipated by two of the components and 40 watts from a third. The client was using ATS heat sinks on the original iteration of the board and wanted ATS to test whether or not the same heat sinks would work with higher power demands.

In the end, the original heat sinks proved to be effective and lowered the case temperature below the required maximum. Through a combination of analytical modeling and CFD simulations, ATS was able to demonstrate that the heat sinks would be able to cool the new, more powerful components.

ATS Field Application Engineer Vineet Barot recently spoke with Marketing Director John O’Day and Marketing Communications Specialist Josh Perry about the process he undertook to meet the requirements of the client and to test the heat sinks under these new conditions.

JP: Thanks again for sitting down with us to talk about the project Vineet. What was the challenge that this client presented to us?
VB: They had a previous-generation PCB on which they were using ATS heat sinks, ATS 1634-C2-R1, and they wanted to know if they switched to the next-gen design with three Altera Stratix 10 FPGAs, two of them being relatively high-powered, could they still use the same heat sinks?

Stratix 10 FPGA

The board that was given to ATS engineers to determine whether the original ATS heat sinks would be effective with new, high-powered Stratix 10 FPGA from Altera. (Advanced Thermal Solutions, Inc.)

They don’t even know what the power of the FPGAs is exactly, but they gave us these parameters: 40°C ambient with the junction temperatures to be no more than 100°C. Even though the initial package is capable of going higher, they wanted this limit. That translates to a 90°C case temperature. You have the silicon chip, the actual component with the gates and everything, and you have a package that puts all that together and there’s typically a thermal path that it follows to the lid that has either metal or plastic. So, there’s some amount of temperature lost from the junction to the case.

The resistance is constant so you know for any given power what the max will be. The power that they wanted for FPGAs 1 and 2, which are down at the bottom, was 90 watts, again this is an estimate, and the third one was 40 watts.

JP: How did you get started working towards a solution?
VB: Immediately we tried to identify the worst-case scenario. Overall the board lay-out is pretty well done because you have nice, linear flow. The fans are relatively powerful, lots of good flow going through there. It’s a well-designed board and they wanted to know what we could do with it.

I said, let’s start with the heat sinks that you’re already using, which are the 1634s, and then go from there. Here are the fan specs. They wanted to use the most powerful fan here in this top curve here. This is flow rate versus pressure. The more pressure you have in front of a fan, the slower it can pump out the air and this is the curve that determines that.

Stratix 10 FPGA

Fan operating points on the board, determined by CFD simulations. (Advanced Thermal Solutions, Inc.)

This little area here is sometime called the knee of the fan curve. Let’s say we’re in this area, the flow rate and pressure is relatively linear, so if I increase my pressure, if I put my hand in front of the fan, the flow rate goes down. If I have no pressure, I have my maximum flow rate. If I increase my pressure then the flow rate goes down. What happens in this part, the same thing. In the knee, a slight increase in pressure, so from .59 to .63, reduces the flow rate quite a bit.

Stratix 10 FPGA

CFD simulations showed that the fans were operating in the “knee” where it is hard to judge the impact of pressure changes on flow rate and vice versa. (Advanced Thermal Solutions, Inc.)

So, for a 0.1 difference in flow rate (in cubic meters per second) it took 0.4 inches of water pressure difference, whereas here for a 0.1 difference in flow rate it only took a .04 increase in pressure. That’s why there’s a circle there. It’s a danger area because if you’re in that range it gets harder to predict what the flow will be because any pressure-change, any dust build-up, any change in estimated open area might change your flow rate.

The 1634 is what they were using previously. It’s a copper heat pipe, straight-fin, mounted with a hardware kit and a backing plate that they have. It’s a custom heat sink that we made for them and actually the next –gen, C2-R1, we also made for them for the previous-gen of their board, they originally wanted us to add heat pipes to this copper heat sink, but I took the latest version and said, let’s see what this one will do. For the third heat sink, I went and did some analytical modeling to see what kind of requirement would be needed and I chose one of our off-the-shelf pushPIN™ heat sinks to work because it was 40 watts.

JO: Is the push pin heat sink down flow from the 1634, so it’s getting preheated air?
VB: Yes. This is a pull system, so the air is going out towards the fans.

Stratix 10 FPGA

CFD simulations done with FloTherm, which uses a recto-linear grid. (Advanced Thermal Solutions, Inc.)

This is the CFD modeling that ATS thermal engineer Sridevi Iyengar did in FloTherm. This is a big board. There are a lot of different nodes, a lot of different cells and FloTherm uses recto-linear grids to avoid waviness. You can change the shape of the lines depending on where you need to be. Sri’s also really good at modeling. She was able to turn it around in a day.

Stratix 10 FPGA

Flow vectors at the cut plane, as determined by CFD simulations. (Advanced Thermal Solutions, Inc.)

These are the different fans and she pointed out what the different fan operating curves. Within this curve, she’s able to point out where the different fans are and she’s pointing out that fan 5 is operating around the knee. If you look at all the different fans they all operate around this are, which is not the best area to operate around. You want to operate down here so that you have a lot of flow. If you look at the case temperatures, remember the max was 90°C, we’re at 75°C. We’re 15°C below, 15° margin of error. This was a push pin heat sink on this one up here and 1634s on the high-powered FPGAs down here.

Stratix 10 FPGA

JP: Was there more analysis that you did before deciding the original heat sinks were the solution?
VB: I calculated analytical models using the flow and the fan operating curves from CFD because it’s relatively hard to predict what the flow is going to be. Using that flow and doing a thermal analysis using HSM (heat sink modeling tool), we were within five percent. What Sri simulated with FloTherm was if a copper heat sink with the heat pipe was working super well, let’s try copper without the heat pipe and you can see the temperature increased from 74° to 76°C here, still way under the case temperature. Aluminum with the heat pipe was 77°; aluminum without the heat pipe was 81°, so you’re still under.

Basically there were enough margins for error, so you could go to smaller fans because there’s some concern about operating in the knee region, or you can downgrade the heat sink if the customer wanted. We presented this and they were very happy with the results. They weren’t super worried about operating in the knee region because there’s going to be some other things that might shift the curve a little bit and they didn’t want to downgrade the heat sink because of the power being dissipated.

Stratix 10 FPGA

Final case temperatures determined by CFD simulations and backed up by analytical modeling. (Advanced Thermal Solutions, Inc.)

JO: What were some of the challenges in this design work that surprised you?
VB: The biggest challenges were translating their board into a board that’s workable for CFD. It’s tricky to simplify it without really removing all of the details. We had to decide what are the details that are important that we need to simulate. The single board computer and power supply, this relatively complex looking piece here with the heat sink, and we simplified that into one dummy heat sink to sort of see if it’s going to get too hot. It all comes with it, so we didn’t have to work on it.

The power supply is even harder, so I didn’t put it in there because I didn’t know what power it would be, didn’t know how hot it would be. I put a dummy component in there to make sure it doesn’t affect the air flow too much but that it does have some effect so you can see the pressure drop from it but thermally it’s not going to affect anything.

JO: It really shows that we know how to cool Stratix FPGAs from Altera, we have clear solutions for that both custom and off-the-shelf and that we understand how to model them in two different ways. We can model them with CFD and analytical modeling. We have pretty much a full complement of capabilities when dealing with this technology.

JP: Are there times when we want to create a TLB (thermal load board) or prototype and test this in a wind tunnel or in our lab?
VB: For the most part, customers will do that part themselves. They have the capability, they have the rack and if it’s a thing where they have the fans built into the rack then they can just test it. On a single individual heat sink basis, it’s not necessary because CFD and analytical modeling are so established. You want two independent solutions to make sure you’re in the right ballpark but it’s not something you’re too concerned that the result will be too far off of the theoretical. For another client, for example, we had to make load boards, but even then they did all the testing.

To learn more about Advanced Thermal Solutions, Inc. consulting services, visit https://www.qats.com/consulting or contact ATS at 781.769.2800 or ats-hq@qats.com.

Q&A: ATS Thermal Engineer Sridevi Iyengar

Sridevi Iyengar

ATS thermal and field application engineer Sridevi Iyengar does CFD modeling (like the one shown above) and on-site consulting for ATS from her location near Bangalore, India. (Advanced Thermal Solutions, Inc.)

Advanced Thermal Solutions, Inc. field application and thermal engineer Sridevi Iyengar recently spoke with Marketing Communications Specialist Josh Perry about her career in engineering and the work that she does for ATS. Iyengar works near her home in Bangalore, India and provides ATS with CFD simulations and on-site support for customers in the region.

In this Q&A, Iyengar speaks about why she became an engineer in the first place, how she came to work at ATS, the type of projects that she works on, the challenges that she faces as a woman in a male-dominated industry, and what it is like working halfway around the world from the engineers at ATS’ Norwood, Mass. campus.

JP: How did you get interested in engineering? How did it all start for you?
SI: I was a good student in high school and in college and my father is a metallurgical engineer. He was a professor in one of the premier institutes in India, the Indian Institute of Science. When we were at the crossroad, during 12th grade, honestly the bright students either went into medicine or engineering and since my math skills were pretty good and I’d been to the Indian Institute of Science a couple of times I had written the entrance examinations for both streams. For engineering, I got into a very good school.

Although I didn’t know about the different disciplines of engineering, I happened to go into chemical engineering because that’s what my rank got me into. I liked it because chemical is kind of a fusion between math and physical phenomena and so that’s where my engineering journey started.

After my Bachelor’s, I wanted to do higher studies. I got married and came to the United States and I wanted to continue in my field of study. I didn’t want to move into software like pretty much everybody else from India when they move to the U.S. I wanted to keep myself different and I had a lot of support for that from my family. The first place I set up home is Norwood, Mass. (in 1993). I was preparing for my GRE and contemplating whether I should take my AGRE but I got positive responses from a couple of schools that I was also keen on getting into. I had options. One was the University of Massachusetts – Lowell, one was Rutgers University and the University of California – San Diego. I chose San Diego.

I was actually accepted into the doctoral program, however at UC-San Diego I liked the fluid mechanics and heat transfer program but then I didn’t want to jump into a Ph. D. without really having real world experience. I wanted to finish my Master’s, work for a few years and then maybe come back if I was interested. Much to my disappointment of my dad, I dropped out of the doctorate program with my Master’s and entered the job scene.

My entry into thermal engineering was kind of by chance. My first job was with Structural Dynamics Research Corporation (SDRC) in San Diego. It was the advanced test and analysis group. I had a background in heat transfer and fluid mechanics and therefore I joined as an intern and they made me do a little bit of this and that. The software associated with the IDEAS master series for electronics cooling was MAYA-ESC electro-systems cooling and TMG (thermal model generator) and we did a project for Cisco Systems in the Bay Area. I worked for about a year and half at ATA-SDRC. SDRC was doing a lot of projects for defense and their core area was becoming more and more defense and I was not a U.S. citizen so it was very difficult for them to assign me to projects because I didn’t have security clearance. At that time I jumped ship and I joined Cisco Systems as a mechanical engineer.

JP: How did you hear about Advanced Thermal Solutions, Inc.? How did you end up working here?
SI: ATS, the company, I knew even when I was at Cisco back in 1999. I was with Cisco until 2005 and at that time I knew about Advanced Thermal Solutions because as a mechanical engineer my job was also to source heat sinks. Also, that it was based in Norwood kind of struck a chord and it remained in my mind. I had known a lot about [ATS CEO, President and founder] Dr. Kaveh Azar because a close colleague of mine had worked closely with Kaveh. And of course Qpedia Thermal eMagazine was/is a very useful online journal.

How I joined ATS was a very, very chance meeting. We moved back to India in 2009 and I was working for an aluminum extrusion company in their thermal management division. It’s a Swedish company called Sapa. Sapa opened an office in India and it was just the sales manager and myself in the Indian team when I started. I worked with Sapa for three years and I was working for their global application team, half working for Sweden and half trying to set up the market in India. At Sapa I did a little bit more than thermal management. Sapa acquired an extrusion facility and also had a machining/anodizing unit. I was exposed to various aspects of manufacturing with regards to aluminium extrusions, fabrication etc., and worked on several other projects, which needed someone who could work with the customers and the manufacturing team at Sapa – sort of like a liaison and the engineering hand of the sales person.

When I quit Sapa, I thought I would go freelance doing electronics cooling consulting and I met one of the sales channel partners for ATS and with him I went and met Dr. Kaveh and Shashwat Shashwat (ATS Product Realization Manager), who were visiting India. This was in May of 2014 and initially it was just supposed to be a ‘hello, how are you’ meeting, but then we started talking and having common professional contacts and interests made it a very interesting interaction. We had lunch and when I came back home that evening Shashwat called me and asked if I was interested in working for ATS. I had no doubts whether I would take this opportunity; I took it with both hands. It’s worked out very well for me so far.

JP: What kinds of projects are you working on for ATS?
SI: There were two things for me, the mandate. One was that we wanted to beef up our presence in India. We already had a sales presence and we were selling heat sinks through Digi-Key and if the engineers know what they want then it’s not a big deal, but it helps them so much to know that there is technical staff from ATS present in India and in Bangalore in the southern region. They call and they say, ‘We’re looking at this heat sink, do you think it’s okay?’ Otherwise they send an email and then they wait for Norwood to reply. So, my role was to support the local sales partners that we have. They do the initial sales call and everything, but then if there’s anything technical they can say, ‘You know, ATS has a presence here? We have this engineer who is in electronic cooling and she has experience.’ I’ve gone to several meetings with them.

Secondly, for the U.S. customers, when it comes to CFD simulations like FloTherm then I work very closely with Norwood. In fact, I’ve done quite a few projects with [ATS field application engineers] Greg Wong or Peter [Konstalilakis], Vineet [Barot] too. A lot of times there are CFD simulations, they face the customers, they get the answers and I run the simulation and build the models here, do the analysis, we discuss the results and they send it to the customer.

JP: Is there a lot of collaboration between yourself and the engineers here in Norwood?
SI: Almost daily. I am online pretty much every day from 6 and on Wednesdays and Fridays we have the team meeting. On other days, I usually chat up with my counterpart on the project and, if it’s a major project, then the discussion is fairly involved. A lot of times, I’ll have a lot of questions so I’ll contact my teammates during my evening and he’ll take it up with the customer, get all the questions answered and by the time morning rolls around everything is sent to me by email and I get through my day. There is a lot of collaboration.

JP: Looking at thermal engineering as a whole, where do you see the industry going?
SI: People realize the importance of up-front thermal design and these folks who are dealing with high-powered components are aware of the importance of up-front thermal design. However there are still a lot of projects in which the hardware engineers are still not zoned into thinking of up-front thermal management, it’s coming in as kind of a ‘Oh it’s too hot, let’s do something about it’ approach. However, I think that mindset is changing a lot and I think the next-gen heat sinks like vapor chambers, heat pipes, and nano-materials will really start making their appearance more and more in thermal solutions because we’re getting to a point where the run of the mill is not cutting it.

JP: Do you see that change coming fairly quickly? In this industry, it seems like things change every day.
SI: The mindset should change because there’s always an aversion towards liquid and PCB. The more we educate people and the fact that we see everything in liquid cooling systems working…It takes some time for them to know that, okay it is a fairly fail-safe method. It will take at least a year or two and it should be running at that time and then people will catch on. It’s not something that can be easily brought on, I think, because generally we know that liquids and electronic components don’t mix. To assure them that it will not mix and there’s no chance of it coming into contact, I think that’s the stumbling block.

It’s market education and also having systems out there functioning, so that we can show them it’s not just theoretical. You have systems in practice and I think that makes a difference. If we can show it in theory, it doesn’t help as much because in theory everything looks wonderful, so we need to show them in practice and all the possible problems that can come up have been addressed and it is working in the field not just in the test lab.

JP: As a woman in a predominantly male-dominated industry, has it been difficult at all?
SI: In India, even back in 1993, we had a lot of engineers who were graduating but a lot of them didn’t stay back in what I call hardcore engineering. People used to go into information technology because they thought somehow it was more suitable for the women in the workforce situation. But I personally, I’ve had a fulfilling time and it is good to distinguish yourself and be different. The work that we do at ATS is hardcore engineering and we have engineers to lead us. We have Dr. Kaveh Azar and Dr. Bahman Tavassoli who have years of engineering experience and yeah sometimes they come down hard on us but that’s because they know what they’re doing. They’ve been there, done that, and they want to extract the best out of you and they want you to think like an engineer always. That’s what is unique of working at ATS.

JP: Do you hope to inspire other women to not only join the field, but stick with the ‘hardcore’ engineering?
SI: Yeah, absolutely. There have been young women who have reached out to me, young engineers who graduated in India, and I tell them have patience and learn the skills needed to get a job. It’s very easy to learn a few programming languages and jump into IT, especially in India right now, but you’re going to be just like anybody else. If your heart really lies in engineering, you should stick on, network, upgrade your skills and you’ll definitely find a job. The first job is everything you need and after that, if you do well there, then the path is smooth.

JP: How has it been for you as a ‘distant worker’ in terms of not being located here in Norwood? We have a lot of great technology like Skype and GoToMeeting, how have you found it being a ‘distant worker’?
SI: Since I interact with the engineers on an almost daily basis it is not that different. ATS engineers and the customers are very understanding of the time difference and accommodate the meetings, if any, so that it is not totally at unearthly hours for me. I also have the freedom to have my own schedule and that is very helpful since I am a working mother. I’ve been to ATS once and so I have met most of the team there.

The only thing is that I don’t have that touch and feel. Sometimes the ATS engineers have the heat sinks/components on their desk and they’re looking at it. A lot of times they will look at it, turn it around and these are things that I will have to accomplish through video call on Skype or the engineers take pictures and send them to me. But it’s not the same. That’s the only drawback. And of course when you folks have your team lunches/picnics … I feel left out.

JP: From our conversation, it sounds like you really like challenging projects?
SI: I think we all like to be challenged once in a while. With involved models, one of the challenges was I’d have to remotely log in and run the model in the 12-core PC and ensure nobody is logged in and I used to run it through the night and post-process it via remote connection. I’d transfer the results over and make the PowerPoint. However I was given a super fast simulation computer locally so all I need is a VPN connection. Even if the VPN connection goes down, FloTherm will not cut off the simulation and it runs through the solve.

Every now and then I support local customers with their heat sink selection requests. Some local customers have asked for training sessions as well, which is something I would like to start fairly soon.

To learn more about Advanced Thermal Solutions, Inc., visit www.qats.com or contact ATS at 781.769.2800 or ats-hq@qats.com.

Integral Modeling Is First Step for ATS Engineers

Integral Modeling

ATS engineers utilize integral or analytical modeling as a first step to solving thermal management issues in a design. [Advanced Thermal Solutions, Inc.]

In July, Future Facilities, a CAD software company, released the results of a survey it conducted of more than 350 electrical engineers (the link to the story is below) on how thermal management relates to reliability in electronics design. The survey coincided with the release of the company’s newest version of its thermal simulation software 6SigmaET.

Forty percent of the surveyed engineers believed thermal simulations for their projects to be too time-consuming or complex. Sixty-two percent of the engineers said that they would rather over-design a project than optimize thermal performance in the design process. In fact, 33 percent of the engineers called thermal issues an “irritation” and would prefer to not deal with them.

Tom Gregory, Product Manager at 6SigmaET, concluded, “It’s clear that a lot of engineers still don’t feel comfortable creating thermal simulations of their designs, a fact which is not being helped by the complex nature of most thermal simulation tools currently on the market.”

The engineers at Advanced Thermal Solutions, Inc. (ATS), a leading-edge engineering and manufacturing company focused on the thermal management of electronics, have long demonstrated that thermal solutions are a critical component to electronics design and that incorporating thermal management early in the design process will lead to a more cost-effective and reliable product.

By incorporating thermal management into the design process engineers optimize time between failure for individual components as well as the overall system. They actually reduce the cost of the system by limiting the need to overdesign it. Well thought out thermal solutions increase the likelihood that the final design will succeed and meet the specifications that were set out at the beginning of the project.

The survey results pointed to CFD analysis as the jumping off point for thermal solutions. But an easier and more efficient way to start the process is with an integral or analytical model, using pencil and paper or a spreadsheet.  In its 3-Core Design Process, ATS has utilized integral modeling as its first step to quickly and easily provide first order solutions and determine whether a design will succeed in meeting its thermal requirements.

Integral modeling, as Dr. Kaveh Azar, founder, President, and CEO of ATS, explained in a webinar (the link is below), utilizes standard equations based on the basic laws that govern thermal engineering: Conservation of Mass, Conservation of Momentum, Conservation of Energy, and Equation of State (i.e. the Ideal Gas Law).

Determining pressure, temperature, and air velocity differentials throughout a system and plugging those numbers into equations that most engineers will remember from undergraduate and graduate training will define the problem that will be faced in designing the system.

Dr. Azar said, “When I focus on integral modeling as I go through the process, you’ll see how easy it is and how broad-spectrumed the applications of these are and this is going to form the first foundation for any kind of analysis that we do in electronics cooling.”

Integral modeling is applicable to any domain and will give a substantiated, independent model to ensure the system is built within the proper parameters. Taking this early step saves time and money that may have been wasted on designing a system that ultimately would not work. Integral modeling also establishes parameters under which the system can be built to save costs after deployment.

Dr. Azar explained, “If we design it for the worst case scenario, we always have the adequate margins and as a result have lesser cost of deployment.”

It is a competitive market. Integral modeling is a quick first step to ensure thermal solutions are part of a design to save on component and system costs. A few quick calculations will have a major impact on the project’s bottom line.

The survey results from Future Facilities can be found at http://www.thermalnews.com/main/news/40-percent-of-electronics-engineers-find-thermal-simulation-too-complex-and-time-consuming.

For more information about the importance of integral modeling and practical applications, watch the webinar with Dr. Kaveh Azar of Advanced Thermal Solutions, Inc. below:

Does the process of thermal design for your next project seem daunting?  Contact us.  ATS offers a  free four-hour consultation in its lab.  Email ATS at ats-hq@qats.com.

An Expert Speaks Out on CFD Modeling of Heat Sinks

Chris Aldham of Future Facilities has something to say about CFD modeling of heat sinks. And he should know after 30 years in the business. Chris will present a webinar for ATS on May 24, 2012 “CFD as a Tool to Perform Heat Sink and System Modeling,” that you can attend for free by registering on Qats.com.

https://www2.gotomeeting.com/register/467986842

We asked Chris to share upfront some general knowledge and opinions on the topic ….

What are some of the recent advances in CFD technology and how might they improve heat sink modeling?

The main advance I’ve seen is the increase in computer power and lowering of computer cost that has occurred over the past few years. It is now possible to solve larger (more grid cells) and more detailed (more objects and better geometrical representation) models and more of them very efficiently. So now representing the detailed geometry heat sinks in a CFD model is easy. Importing MCAD heat sink geometry and using that geometry directly in the software ensures an accurate representation of the heat sink.

The other advance is the automation possible in specialized tools such as 6SigmaET. The mesh necessary to represent the heat sink is determined automatically within the software it doesn’t rely on the user creating a good mesh.

These two trends seem set to continue so it will be possible to model increasingly complicated heat sink designs.

Meshing is very core to CFD modeling. What are the do’s and dont’s when it comes to meshing heat sink models?

I think there are two aspects to consider when meshing a heat sink. The solid geometry must be accurately captured to ensure the heat spreading and conduction through the base and up the fins is accurately represented. Then the airflow between the fins must be accurately captured. This invariably requires a fine mesh at least 3 cells between the fins and maybe more depending on the gap size.

What are some of the benefits from developing a high quality CFD model of a heat sink?

At first sight heat sinks seem quite simple in function but their interaction with the components they are cooling and the air flow around them is quite complex. The heat spreading of the heat sink base can subtly change the thermal resistance of the component. The increase in surface area the heat sink provides improves heat transfer but also represents an increased resistance (increased pressure drop) to the airflow. So a good heat sink design must balance heat spreading, heat transfer and pressure drop. As a detailed CFD model can represent all these aspects accurately in the situation in which it will be used it can be the only way to optimize them before the heat sink is manufactured and tested.

Can you cite any examples where your CFD tools led to improved heat sinks solutions?

We have published a couple of examples together with ATS Europe who have used 6SigmaET in a number of projects. One was an unusual heat sink design on an LED replacement for a traditional light bulb where a 14% improvement in lamp performance was produced (as well as a much nicer looking design in my opinion) by changing the heat sink design. This work also showed good agreement between 6SigmaET simulations and measurements performed on the real devices. See images below.

How long does it take a typical engineer to master CFD modeling? Are there any innovations in training?

I’ve been doing CFD for over 30years and I’m not sure I’ve mastered it yet. Fortunately engineers do not have master CFD modeling today as some CFD software products are focused on specific applications and these can really present CFD in a very usable form. Of course it helps if the engineers have some idea of the physics of fluid flow and heat transfer but much of the numerical work in CFD can be preset, automated and hidden away. This has been especially true in the field of electronics cooling where specialized software has been around for decades. These tools can be learned in a few days and users can be proficient in a few weeks.

How is Future Facilities different from its competitors?

Future Facilities is highly focused on a small number of related application areas. We produce software for design, operation and management of data centers which includes CFD modeling of the airflow and temperatures as well as other non-CFD analysis modules. We also use the software in our engineering consultancy group providing services that ensure the software development is focused on exactly what is needed and making it easy and efficient.

6SigmaET is a recent product focused on electronics cooling and integrated into our data center suite. Like the whole software suite it presents the user with a set of specialized intelligent objects which represent the real things encountered in electronics (pcbs, fans, heat sinks, power supply, components, etc.). As every object knows what it is, it knows how to behave and this can make creating a model very intuitive for the users. It also allows us to automate the meshing rules for each object so we can ensure a heat sink, for example, is meshed correctly.

I believe the many years of experience we have in using and developing CFD products alongside a strong focus on particular application areas and a desire to make complex technology available to engineers (expert and beginner, full-time or occasional users) makes us very different from other CFD companies.

Dr. Chris Aldham has worked in computational fluid dynamics (CFD) for over 30 years (starting with PHOENICS at CHAM with Prof. Brian Spalding) and for more than 20 years in the field of electronics cooling. After 16 years at Flomerics, Chris joined Future Facilities as a Product Manager responsible for 6SigmaET electronics cooling simulation software which is part of a suite of integrated software products that tackle head-on the challenges of data center lifecycle engineering (including equipment design analysis) through the Virtual Facility