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Re: [sparta-users] Using SPARTA grids for a nonhomogeneous temperature surface
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From: Sarah P. <sar...@vk...> - 2023-06-05 07:52:24
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Hi Steve, The current plan is have SPARTA read the surface temperature when the geometry is loaded at the beginning of the run before the simulation starts. The temperatures could be assigned in a material solver/FEM software. This would remove the need to assign the temperature in SPARTA and it would just be an attribute of each element. I would love to hear your thoughts and advice on the method. I am unsure how to utilize this method with current SPARTA commands, to me it seems that the "fix surf/temp" command may be a dead end right now. Sincerely, Sarah Peterson Von Karman Institute ________________________________ From: Steve Plimpton <sj...@gm...> Sent: Friday, June 2, 2023 6:17 PM To: Sarah Peterson <sar...@vk...> Cc: geo...@dl... <geo...@dl...>; spa...@li... <spa...@li...> Subject: Re: [sparta-users] Using SPARTA grids for a nonhomogeneous temperature surface Warning: This is an email sent from outside the von Karman Institute. Do not open links or attachments unless you were expecting them and have verified they come from a safe source. Contact IT in case of doubts. If you have 10,000 surface elements, how are you thinking you want to assign a temperature to each one? Steve On Thu, Jun 1, 2023 at 8:45 AM Sarah Peterson <sar...@vk...<mailto:sar...@vk...>> wrote: Hi Steve, The goal is to have static temperature values along a single DSMC run assigned at the beginning of the simulation. Thank you for your help. Sincerely, Sarah Peterson Von Karman Institute ________________________________ From: Steve Plimpton <sj...@gm...<mailto:sj...@gm...>> Sent: Thursday, June 1, 2023 4:53 PM To: Sarah Peterson <sar...@vk...<mailto:sar...@vk...>> Cc: geo...@dl...<mailto:geo...@dl...> <geo...@dl...<mailto:geo...@dl...>>; spa...@li...<mailto:spa...@li...> <spa...@li...<mailto:spa...@li...>> Subject: Re: [sparta-users] Using SPARTA grids for a nonhomogeneous temperature surface You don't often get email from sj...@gm...<mailto:sj...@gm...>. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> Warning: This is an email sent from outside the von Karman Institute. Do not open links or attachments unless you were expecting them and have verified they come from a safe source. Contact IT in case of doubts. Sorry for the confusion. You are both correct that surf-style variables are not yet implemented. It is something we have thought about, but not yet done. They would probably work like grid-style variables, where the center point of a triangle could appear in the formula so that the value of the variable could be a function of the location of the triangle as well as of time, some per-surf compute value, etc. If that would be useful for your model, let me know. However, per-surf custom vectors are supported, which is what is used by fix surf/temp and is supported by the various surf_collide and surf_react models. They are more general than a surf-style variable would be, since you could write any code you wish (e.g. a new or modified fix) to calculate a per-triangle temperature. You haven't explained how conceptually you want to set per-triangle temperatures, and whether they are static or dynamic values. If you explain, I could likely advise the easiest way to do it. Steve On Thu, Jun 1, 2023 at 7:05 AM Sarah Peterson <sar...@vk...<mailto:sar...@vk...>> wrote: Dear Steve, Thank you for the thorough explanation. It was very helpful. I'm not sure what I understand by a surf style variable. Looking through the documentation the only method I found to assign a temperature to an element involves using "compute surf" to get the total energy and using "fix surf/temp" to set some sort of temperature. That command uses group surf IDs to set the temperature of each section. So it can't assign temperatures on a single element basis, it can only handle groups of them. Is that what you meant by that? How does that method work to assign temperatures to individual elements? I'll admit this is my first time working with SPARTA so I am not completely familiar with every aspect of the program. Sincerely, Sarah Peterson Von Karman Institute ________________________________ From: geo...@dl...<mailto:geo...@dl...> <geo...@dl...<mailto:geo...@dl...>> Sent: Thursday, June 1, 2023 9:47 AM To: sj...@gm...<mailto:sj...@gm...> <sj...@gm...<mailto:sj...@gm...>>; Sarah Peterson <sar...@vk...<mailto:sar...@vk...>> Cc: spa...@li...<mailto:spa...@li...> <spa...@li...<mailto:spa...@li...>> Subject: Re: [sparta-users] Using SPARTA grids for a nonhomogeneous temperature surface You don't often get email from geo...@dl...<mailto:geo...@dl...>. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> Warning: This is an email sent from outside the von Karman Institute. Do not open links or attachments unless you were expecting them and have verified they come from a safe source. Contact IT in case of doubts. Dear Steve, thanks for the explanation, getting the terminology clear was helpful for me as well. RE: using a surf-style variable formula and the variable command: as far as I know, surf-style variables are still not implemented in the code? (at least looking at the master branch; lines 445-446 in variable.cpp) Mit freundlichen Grüßen Dr. Georgii Oblapenko Postdoctoral Researcher Alexander von Humboldt Stiftung Fellow Institut für Aerodynamik und Strömungstechnik Deutsches Zentrum für Luft- und Raumfahrt (DLR) ________________________________ From: Steve Plimpton <sj...@gm...<mailto:sj...@gm...>> Sent: 31 May 2023 22:33:12 To: Sarah Peterson Cc: Oblapenko, Georgii; spa...@li...<mailto:spa...@li...> Subject: Re: [sparta-users] Using SPARTA grids for a nonhomogeneous temperature surface Hi - the terminology in this thread is somewhat confusing. There is only a single volumetric grid in SPARTA, though it can adapt over time. There is also a collection of static surface elements. Grid cells can be assigned to grid groups. Surface elements can be assigned to surface groups. In both cases a "group" is simply a set of one or more surface elements (or grid cells). There is a hard maximum of 32 grid groups and 32 surface groups. We don't know of any use cases where more groups are needed. What you are asking about (I think) is assigning temperatures to individual surface elements. That has nothing to do with groups. A surface temperature is only currently used by surface collision and reaction models (surf_collide and surf_react commands). All the existing models only define it as the resolution of a single surface elements. If you want the temperature to vary across a single triangle, then you should simply break the big triangle into smaller triangles (which you input to SPARTA), and define a temperature for each small triangle. You can define per-triangle temperatures in 2 ways. Using a surf-style variable formula and the variable command. Or using the fix surf/temp command which computes termperatures (per triangle) via a formula using energy deposited onto the triangle as tallied by a compute or fix. If you have some other model in mind for computing the temperature of a triangle, then you could implement a new fix similar to fix surf/temp. Or posslbly you could add it as option to the existing fix surf/temp command. E.g. use a different formula. Steve On Wed, May 31, 2023 at 7:18 AM Sarah Peterson <sar...@vk...<mailto:sar...@vk...>> wrote: Thank you for the link. That is unfortunate, I was hoping it was an arbitrary constraint due to concerns about computational power and memory usage. I found this message (Thread: [sparta-users] Modify SPARTA to allow more than 32 surface groups? | SPARTA (sourceforge.net)<https://sourceforge.net/p/sparta/mailman/sparta-users/thread/CAMkvQcT2u7Lst3r3WxnEPpnM7%2B2%2B0_nrmPU4Svg5G4bj-HDMRw%40mail.gmail.com/#msg36445633>)that had a similar issue to me though I'm not sure I understand the proposed solution. I thought surfaces were also subject to the 32-group limit as well. Thank you for your help. Sincerely, Sarah Peterson Von Karman Insititute ________________________________ From: geo...@dl...<mailto:geo...@dl...> <geo...@dl...<mailto:geo...@dl...>> Sent: Wednesday, May 31, 2023 2:46 PM To: Sarah Peterson <sar...@vk...<mailto:sar...@vk...>>; spa...@li...<mailto:spa...@li...> <spa...@li...<mailto:spa...@li...>> Subject: Re: Using SPARTA grids for a nonhomogeneous temperature surface You don't often get email from geo...@dl...<mailto:geo...@dl...>. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> Warning: This is an email sent from outside the von Karman Institute. Do not open links or attachments unless you were expecting them and have verified they come from a safe source. Contact IT in case of doubts. Dear Sarah, this is a relevant discussion: https://github.com/sparta/sparta/issues/260 So it seems there is no way around that except by writing your own code to assign surface temperatures. Mit freundlichen Grüßen Dr. Georgii Oblapenko Postdoctoral Researcher Alexander von Humboldt Stiftung Fellow Institut für Aerodynamik und Strömungstechnik Deutsches Zentrum für Luft- und Raumfahrt (DLR) ________________________________ From: Sarah Peterson <sar...@vk...<mailto:sar...@vk...>> Sent: 31 May 2023 12:02:25 To: spa...@li...<mailto:spa...@li...> Subject: [sparta-users] Using SPARTA grids for a nonhomogeneous temperature surface Hello, I am a student researcher working with your program to try and couple it with a material solver to model systems with a nonhomogeneous temperature distribution. However, I am having issues with the number of grids that SPARTA allows. My initial plan was to use the "group surf" command to generate grids on the surface and assign them different temperature values with "fix surf/temp", but SPARTA only allows for 32 grids to be active at one time. On large objects this would be rather imprecise. Is there a method to bypass this limit or an alternative method to reach my desired goal? Thank you for your help. Sincerely, Sarah Peterson Von Karman Insititute _______________________________________________ sparta-users mailing list spa...@li...<mailto:spa...@li...> https://lists.sourceforge.net/lists/listinfo/sparta-users |
