Simulating and Optimizing Heat Transfer
On-demand Web Seminar
Join us for a complimentary web seminar, where the presenter will discuss the complexities of designing and integrating cooling into injection molds while still managing heat and what this means for the overall design of the finished product.
To illustrate this, the presenter will show you how easy it is with FloEFD to prepare a product design for analysis, analyze it and then evaluate the results, The presenter will then go on to show you how to perform “what-if” analysis by simply modifying the MCAD geometry and viewing the simulation results for the new model.
What You Will Learn
- How to quickly perform analysis using a FloEFD wizards
- Visualize heat distribution in a virtual 3D environment
- Understand the impact of design changes and how it can effect temperatures
- Export detailed reports to Microsoft’s Word and Excel
About the Presenter
Alexandra Francois-Saint-Cyr is the Applications Engineering Manager for North America at Mentor Graphics, Mechanical Analysis Division (Previously Flomerics). For the past 8 years, she has been working on promoting the use of the Mentor Computational Fluid Dynamics (CFD) software by conducting training classes, seminars and software demonstrations.
After graduating from ESSTIN, France’s State Graduate School of Engineering back in 1997, Alex studied to improve passenger comfort in the trains at Alstom Transport by using CFD software FloVENT. In 1999, she moved to the United States where she received her MSME from the University of Central Florida. There she worked on a meso-scale centrifugal compressor project, her research leading to the ‘Best Technical Paper’ award in the Advanced Energy Systems Division at the International ASME show in 2000
Who Should View
- Design Engineers
- Mechanical Engineers
- Product Design Managers
- Engineers who are currently using MCAD and are interested in a CAD-embedded analysis solution
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Q and A Transcript
- Q: How much computing power do you need to run FloEFD?
- A: FloEFD runs on both 32 and 64bit Windows Operating Systems. It requires a minimum of 512Mb of RAM to run.
- Q: Can FloEFD be run from an external mobile hard drive?
- A: The software itself must be installed within the Windows OS and the CAD system. If both are running fine from an external HDD, FloEFD should run as well. Running FloEFD models from an external HDD should also work as long as the user has access rights.
- Q: Refrigeration, can FloEFD be used to predict inside fridge temperature from the cold 'element' (evaporator)?
- A: FloEFD handles the 3 modes of heat transfer: conduction, convection and radiation so it will be able to compute the internal fridge temperature. However, FloEFD does not support multi-phase flow so you would not be able to calculate the change of phase happening in the evaporator.
- Q: Is it possible to export results from specific areas let's say a curved surface?
- A: Yes, you can export data from any surface by either setting up a Surface Goal or requesting a Surface Parameter. All the variables computed at this surface, i.e, temperature, heat transfer rate, etc., are then exported to an Excel spreadsheet.
- Q: Pipe-soil thermodynamics interactions? Batches?
- A: If this question is related to DEM solutions (discrete particle flows), then FloEFD does not support them because DEM is not based on Navier-Stokes equations. However, in some cases it might be possible to describe bulk material flow behavior using a non-Newtonian fluid model such as Bingham for use within FloEFD. In that case, you will need to identify the material property data for the model to obtain the right results
- Q: Could FloEFD replace FloTHERM in small handheld (PDA, cell phones etc) device thermal design process?
- A: As a general purpose CFD tool, FloEFD can be used for many applications including mobile phones or PDA’s. It is always important to think about the thermal design process when choosing the best tool for the task at hand. For example, complexity of the model is a key determinant. One of FloTHERM’s primary assets is its ability to handle thousands of objects and attributes very efficiently while still allowing for high-speed solution and parametric analyses to be performed. Therefore, we recommend that you decide on the best tool for the task at hand on a case-by-case basis.
- Q: Few words on the size of the computational domain, please? How are the conditions (pressure, velocity) on boundaries prescribed?
- A: For this analysis, the computational domain was the same size as the tool and the lens in order to be more conservative (no heat transfer to the outside world). If the domain was extended around the tool and lens, then the faces of the domain would be open to sea level pressure conditions and to a 20°C stagnant air temperature. Note that all these settings can be adjusted if the boundary conditions are different.
- Q: I have CATIA v5r17, can I get FloEFD for this?
- A: Definitely! The product that supports CATIA V5 is called FloEFD V5. You can find additional information on FloEFD V5 here http://www.mentor.com/products/mechanical/products/upload/floedf-v5.pdf
- Q: Can you specify pressure gradient at water outlet?
- A: Yes, you can do that.
- Q: Can you explain how the minimum gap size controls the minimum mesh size?
- A: Using information about the model geometry, such as the minimum gap size, FloEFD further constructs the mesh by means of various refinements, i.e. splitting of the basic mesh cells into smaller cells, thus better representing the model and fluid regions.
- Q: You mentioned that FloEFD outputs detailed reporting to Word and Excel, what version of Microsoft Office does the software use?
- A: FloEFD supports Microsoft Office 2000, 2003 and 2007 for the reporting capabilities.
- Q: Do we have a zero-thickness wall (internal surface) with thermal properties?
- A: FloEFD applies boundary conditions to 3D solids only. Note that, for thin elements such as thin walls, FloEFD has an internal treatment which allows for conduction in these walls to be computed without mesh overhead.
- Q: Can FloEFD simulate long-pipeline systems (interconnected or not)?
- A: FloEFD solves for flow and heat transfer in 3D so it can definitely solve for pipeline systems, depending on the system size.
- Q: What if I have an application similar to your demo, but I want to consider the effect of the environment around it as well?
- A: There are two things you could do to consider the surrounding environment. 1. You could set up heat transfer coefficients at the tool and lens surfaces, or 2. You could expand the solution domain further around the tool and lens and let FloEFD calculate the heat transfer coefficients at the solid surfaces along with the radiation exchanges, if applicable.
- Q: Can FloEFD analyze transient conditions or time based events or is it just steady-state?
- A: Yes, FloEFD can also solve transient analyses.
- Q: How about the thermal properties of the porous media? - can we account for those?
- A: Yes, you can attach a material property to a porous media and it will conduct heat.
- Q: Can FloEFD run mesh (distribution) networks?
- A: If this question is related to computer networks, FloEFD does not support distributed memory systems such as clusters at this time. If this question refers to pipe network distribution, then we suggest you take a look at 1D codes because they would be more appropriate for the task.
- Q: How long does it take to learn your software?
- A: New FloEFD users come up to speed quickly – some users report that they were able to set-up and start analyzing problems in under 8 hours. Users who have knowledge of the subject matter are able to fulfill analysis requirements with FloEFD even if they did not get a chance to attend a training class. However, we still recommend getting trained whenever possible as our technical staff will advise you on how to maximize the benefits of using this design evaluation tool on a day-to-day basis. As a first step, we recommend that you download the 60-day trial version of FloEFD from our website so you can test the technology first-hand.
- Q: We manufacture air ducts and we perform simulations of fluid in the pipelines, we use a mesh diffusion to spread the air, my question is do we need to mesh with the details (holes)? thanks
- A: You can use both approaches if needed. 1. Keep the mesh with a detailed representation but the solution may take longer to complete or 2. Use a Porous Media element with the corresponding pressure drop. FloEFD allows for loss coefficients in the X, Y and Z directions to be applied in order to mimic the flow behavior of filters, meshes, etc. By the way the FloEFD manual includes a validation example showing how a porous screen behaves when facing a non-uniform stream.
- Q: Our Company carries out all of its CAD work using Siemens NX. Can I use your software with our CAD models?
- A: Yes, FloEFD reads native CAD data directly from all major CAD systems including Siemens NX, SolidEdge, Autodesk Inventor, etc. without the need for prior data conversion.
- Q: Does FloEFD use k-e turbulence model? In addition, can 3D flow separation be handled properly/accurately in external flows?
- A: FloEFD uses a modified k-e turbulence model which handles flow separation very accurately. To illustrate the accuracy level, the FloEFD manual includes a validation example showing flow over a cylinder with the Reynolds number varying from 40 to 100,000.
- Q: What about external analysis?
- A: Yes, FloEFD can do external analysis. For example, the software can be used to compute drag and lift coefficients.
- Q: Does FloEFD automatically use multiprocessors or does it need a special license?
- A: FloEFD by default, allows a user choose the amount processors they want dedicated to running the software and does not require extra licensing to do so.
- Q: Did the LaserCUSING tool take longer to solve than the borehole tool? If so, how long for both steady state and transient?
- A: Because of its complexity, the LaserCUSING tool took longer to solve than the borehole tool. The steady state model took about 1.5h to solve while the transient model took 6h to solve.
- Q: Will FloTHERM be phased out?
- A: No. FloTHERM is the market leading software for electronics cooling applications and it is in use at 75 of the top 100 electronics companies in the world. FloEFD is our general purpose CFD tool which can be used for multiple applications. Each product meets the needs of a different market; therefore, both products are here to stay.
- Q: Can FloEFD model both multi-flow and multi-phase?
- A: FloEFD handles mixing fluids as long as they are miscible. It does not currently handle multi-phase flow. If you are interested in learning more about mixing fluid, please note that it will be the topic of the next FloEFD webinar. http://www.mentor.com/products/mechanical/events/simulating-optimizing-mixing-processes-webseminar
- Q: Can FloEFD simulate compressible flow?
- A: Yes, FloEFD can simulate compressible flow and shock waves. The FloEFD manual contains a few validation examples showing supersonic flow in a channel and over a conic body.
- Q: How is the convective film coefficient calculated for initial boundary conditions?
- A: FloEFD uses a Finite Volume Approach to compute local heat transfer coefficients at the solid-fluid interface. These values will depend on the boundary conditions defined within the model. For the surfaces in contact with the computational domain, it will depend on the wall condition attached. The walls can be defined as adiabatic, exposed to a fixed heat transfer coefficient or a fixed temperature.
- Q: Could you comment on the criteria for choosing constant temperature vs. constant flux boundary conditions on the heat source surfaces? In case of a high surface power density a constant temperature is appropriate. However, at low surface power density none of the above choices are accurate.
- A: When doing a CFD analysis, setting the correct boundary conditions is always the key to obtaining accurate results. Sometimes, you need to make assumptions on the boundary conditions due to the complexity of the physics involved. Comparing experimental results to analysis results in this case can help define more appropriate boundary conditions.