I am currently writing my Bachelor-Thesis with OpenFOAM and this video is really helpful. It gets me an good overview for post processing. A tutorial well made. Thank you for the good work here :)
@AirShaper3 жыл бұрын
Thank you, it's very kind of you to let us know the video was helpful - good luck with your Thesis!
@obkf-too3 жыл бұрын
Finally someone explaining things the right way. Thanks for the tutorial.
@AirShaper3 жыл бұрын
Thank you very much Oussama!
@eduserenza3 жыл бұрын
Very clear presentation, I am thinking in start study CFD with OpenFoam, I did not know about that big capability of OpenFoam. Really is impressive!
@AirShaper3 жыл бұрын
Thanks Eduardo, yeah OpenFOAM is really impressive - best of luck!
@user-vz9le3de5t10 ай бұрын
Thanks for this, I am in the process of validating the drivAer case (notchback) with our commercial solver.
@docd77793 жыл бұрын
Clear, concise, informative and interesting - excellent.
@AirShaper3 жыл бұрын
Thank you very much Doc!
@IRC20053 жыл бұрын
Beautifully clear presentation.
@AirShaper3 жыл бұрын
Thanks a lot Glig
@thucpham45983 ай бұрын
Clear and informative! Thank you so much!!
@AirShaper3 ай бұрын
Thank you, you're most welcome!
@Rahmahhusayn7 ай бұрын
hello, nice and understandable tutorial, thank you sir. I would like to ask why we need to subtract with wallshearstress? is the P*A the total forces already? so that if we want to get the pressure force need to subtract with wallshearstress?
@AirShaper7 ай бұрын
The total force on a surge is the sum of the perpendicular force (pressure) and tangential force (friction. That is why you need to sum them. The minus sign is because of conventions on how to define force direction, has no specific meaning.
@MountainPassPerformance11 ай бұрын
Wonderful, thank you!
@MarcelNKemet4 ай бұрын
NB: wallShearStress vector data is not included by default. You need to specify it as a function in system/controlDict.
@francescapalanza24804 ай бұрын
Hello, sorry how do I do this?
@marvin17113 жыл бұрын
Thank you so much! It really helped me with my project!
@AirShaper3 жыл бұрын
You're most welcome!
@gamergoohooАй бұрын
Thank you !
@Robert-dv3uz Жыл бұрын
how do we came from cp=(p-p_infinity)/(0.5*rho*U_infinity^2) to (p+0.5*rho*U_mag^2)/(0.5*rho*U_infinity^2)?
@AirShaper Жыл бұрын
In OpenFOAM, the pressure values are relative to a reference pressure we set ourselves (p-infinity). And we set p_infinity to 0 in our simulations, so it drops from the equation.
@LT728843 ай бұрын
question, in paraview 5.12.0-RC, when you search for "generate normals" it is greyed out and i can not select it? why would that be?
@HoaiThanh-wm6ze5 ай бұрын
why is the total force calculated by (p*normal-wallshear)*rho. as I know this is need by equation (p*normal+wallshear)*rho. what is the correct?
@architsaxen3 ай бұрын
Can you please let me know how can I clear a surface feature error for open manifolds in my geometry?
@nikhilbhamare67613 жыл бұрын
Yo very good bro. Love your vdeos.👍🏻
@AirShaper3 жыл бұрын
Thanks Nikhil, I hope it's useful!
@andrisitepu4750Ай бұрын
Can you simulate heat transfer on the hatsink?
@LT728846 ай бұрын
Hello : ) I love this video as well as your other videos. I JUST started learning cfd and fea this week. It is a very overwhelming subject. With that in mind, do you have the video that shows how you made the "virtual wind tunnel", meshing and the use of OpenFOAM? Thank you :)
@AirShaper6 ай бұрын
We don't have a video on this we have some very old OpenFOAM course material: airshaper.com/courses
@LT728846 ай бұрын
@@AirShaper thanks for the link, ill at least check that out haha.
@ahmetkirhan58965 ай бұрын
Hello Sir, Thanks a lot for this tutorial. I have a question. What is the formula for Cp for compressible flow and how can we apply it to paraview?
@saveriolecce58883 жыл бұрын
Hi. I think your channel is very interesting. I have one question about this video. When you computed the total force acting on the vehicle, why are you subtracting instead of summing the wall shear stresses? Is that becasue you are interested only in the pressure forces rather than in the effect of both pressure and friction or I am just missing something?
@AirShaper3 жыл бұрын
Dear Saverio, good question - I don't know! If I look purely at the friction forces and integrate them across the car, then I get a negative value in the driving direction. That is physically not possible. When I apply the minus sign, it matches perfectly with the forces we calculate in OpenFOAM. My guess is that perhaps this has something to do with the normals, which can be inside-out on the surface (because the surface you see is actually the boundary of the air volume, not really the surface of the car). If you find out more, thanks for letting me know!
@peterb8387 Жыл бұрын
Why does the data from OpenFOAM (pressure, velocity, etc.) sometimes now show up? Just a grey block in the display portal/window? I use Salome to make my meshes. Typically I past the new mesh in another case file and usually run into this issue.
@AirShaper Жыл бұрын
Sometimes it could be because you need to go to the last time step, or select the decomposed case data
@alvarolleonart6662Ай бұрын
Hi there! How could I obtain the wallShearSress if I already did the simulation and it does not appear in paraView? Do i need to change any file or include "wallshearstress" somewhere? It would be very helpful to know some information, I need this variable to calculate my forces on my 3D F1. Thanks!
@AirShaperАй бұрын
You need to run a separate post processing command in Open foam to get that field
@hessmess95043 жыл бұрын
Excellent. Thank you :-)
@AirShaper3 жыл бұрын
Thank you very much Hess!
@diegoandrade3912 Жыл бұрын
Bravo!!!
@AirShaper Жыл бұрын
Thanks Diego!
@jaydeepchawda91053 жыл бұрын
Very helpful
@AirShaper3 жыл бұрын
Thank you Jaydeep!
@user-mv6ip3sw7q7 ай бұрын
Thanks for your services. I have a question. In many videos about calculating drag force, during the calculator step, they often don't multiply by density. Can you explain this part in detail? I'm not good at English. Thanks read my question.
@AirShaper7 ай бұрын
It depends on how they store the pressure field. In some calculations, the pressure field p is the real pressure. In other calculations, it is the normalized pressure (divided by the density). It depends on which solver you use, if you use a reference pressure, compressible flow, etc.
@user-mv6ip3sw7q7 ай бұрын
Thanks :)@@AirShaper
@ilserojas91523 жыл бұрын
Thank you so much for this video, it was very clear and helpful. When I try to use Surface LIC in the internal mesh, Paraview suddenly closes and the Output Messages window pops up but with no messages inside. Could you please explain what are the possible reasons and solutions to this? Thanks in advance (:
@AirShaper3 жыл бұрын
Ow haven't had that before yet - surfaceLIC perhaps only works on surfaces (a slice, object surface, ...). Perhaps that is the reason?
@esarworks496311 ай бұрын
Hello, Thanks for the tutorial, its very helpful for someone new to ParaView. I wanted to know if you could share some info on what computational resources were need to run the DrivAre model. Runtime, CPU, hours, etc. that kind of thing.
@AirShaper10 ай бұрын
This sim would typically take around 3 hours on a machine with around 170 virtual CPUs and a few 100gb of memory. But you can run it on smaller machines as well.
@simprolougebycadkonstrukti465411 ай бұрын
Hello, very nice tutorial! Thank you! One question: Do the forces and tourque relate to the Center origin of the car? So to coordinates of 0 0 0 in world space? So if my cog would be middle of front axis in the car 3d model, would the force pull on that point? Hope you understand my question…
@AirShaper10 ай бұрын
Yes, the forces and moments relate to 0 0 0. If you want to change that, you can do a translate operation on the entire internal mesh, to reposition the origin.
@michielvanstaden26983 жыл бұрын
Big Thumbs Up
@AirShaper3 жыл бұрын
Thanks Michiel!
@TheBadoumba3 жыл бұрын
Hi Wouter. Thanks for the video. Could you explain the origin of the difference between AirShaper and Paraview visual regarding the total pressure bubble (additional layer on the surface of the car). Is it something we can correct somehow in Paraview? Thanks!
@AirShaper3 жыл бұрын
Hi Sylvain, for the AirShaper report, we first cut away the cells that are touching the surface of the object (in OpenFOAM). This avoids having the entire object surrounded in a "pressure bubble". We haven't found a way to do that in Paraview, but we stopped looking after we solved it in OpenFOAM directly. I would guess that with some creativity this should be possible in Paraview as well.
@TheBadoumba3 жыл бұрын
Ok Wouter 👍 The result is perfect! Great work.
@nilmarosa24 Жыл бұрын
hello, one question where can I download the file to follow up the tutorial?
@AirShaper Жыл бұрын
Dear Nilma the Drivaer data is not available. But currently, you get a coupon for a free simulation when you create an AirShaper account. And that one comes with the OpenFOAM result data you can use for this tutorial!
@pepijnhuvenaars3 жыл бұрын
@9:45 I can't see which symbol you type between kHat and coords.
@AirShaper3 жыл бұрын
it's a minus sign! --> ...kHat-coords)
@praveen667 Жыл бұрын
Can you help me to get the access of the car model you used sir? pls?
@braedenswid80843 жыл бұрын
Great video! How do I know if my data is normalized with density? Is this always the case? Thank you again.
@AirShaper3 жыл бұрын
Hi Braeden, the field files of OpenFOAM don't provide you with that information I'm afraid. The best way is to check, if you have the case files, in the constant properties & controlDict files which density & solver were used. Then, checking OpenFOAM documentation, you can deduct if the density was normalized. I'm not sure if it's always normalize by the density, it could be!
@broniaa15362 жыл бұрын
Hi, thanks for this video, it's been very helpful. Can you clarify one thing for me please? After integration of force and torque, how do I use the single integrated vector in following calculations instead of a "map" of force vectors?
@AirShaper2 жыл бұрын
Hi! I don't think I completely understand the question - what do you mean with the single integrated vector (force & torque are not combined, I think, in our video?)?
@broniaa15362 жыл бұрын
@@AirShaper No no I meant using i.e. resulting (so integrated) force vector instead of force field. But I can see that after IntegratingVariables it already uses the single vector in further calculations. Thanks again
@broniaa15362 жыл бұрын
@@AirShaper Do you maybe have some hints on calculating the center of pressure? I already calculated the arm of the force and not sure how to proceed
@VinnieDreher3 жыл бұрын
Te amo !
@AirShaper3 жыл бұрын
Hope this all makes you go faster! I saw you race motorbikes --> be sure to check our interviews with Mv Agusta: airshaper.com/videos/race-talk-with-mv-agusta-top-aerodynamic-priorities-for-moto-gp-bikes/video/BUkaejkHRn8 airshaper.com/videos/race-talk-with-mv-agusta-how-to-improve-moto-gp-aerodynamics/video/fGNdMaVft_w
@piereligiodisante11 ай бұрын
I haven't wallshearstress in my openfoam simulation. I generated it using Xsim, maybe it's not the best way. How do you recommend to run a simulation for this use case?
@AirShaper11 ай бұрын
I haven't heard of Xsim before. In OpenFOAM, the wallShearStress is generated during post processing with a separate command.
@piereligiodisante11 ай бұрын
@@AirShaper that's great to know, thanks. Xsim is a nice web based (runs locally) GUI tool that prepares the scene for openfoam, which then you'll run on your machine. But for some reason they didn't include the wallshearstress in the post processing, but the calculation of drag and lift coefficients is there. But I guess it's wrong
@AirShaper11 ай бұрын
@@piereligiodisante Interesting, I hadn't heard of it before, thanks a lot! Hm, then best to double check all the calculation settings if the values are wrong :)
@piereligiodisante11 ай бұрын
@@AirShaper i assume it’s wrong because there is no wallshearstress output, so that isn’t used for sure
@AirShaper11 ай бұрын
@@piereligiodisante It could still be correct, the OpenFOAM "forces" and "forceCoeffs" might take wallShearStress into account (without writing that field)
@turtlemicro3 жыл бұрын
20:39 Why do you multiply the static pressure with the density? Isn't the calculated pressure in OpenFOAM the static pressure? Is it possible to use the formula for the incompressible case cp = 1 - (c / c_infinity)^2 ? Thanks for the great video!
@AirShaper3 жыл бұрын
By default, OpenFOAM (at least for the simpleFOAM solver) will write the normalized pressure, which means it is divided by the density. To obtain the real pressure (and thus the correct force) you indeed need to multiply it with the density. You can indeed calculate the pressure coefficient as well (which can be done using both the static and the total pressure) to get a "relative" distribution. When we show "pressure clouds" in our reports, we use an isosurface for the total pressure coefficient for a value of 0 (which nicely shows you the wake!). There are commands in openfoam to calculate the total pressure as a new field - those are pretty useful as well.
@turtlemicro3 жыл бұрын
@@AirShaper okay, makes sense. Thank you very much!
@pedrobrito80803 жыл бұрын
Hello, I enjoyed the presentation very much. Very helpful, as I´m new to car aerodynamics and OpenFoam. Can you clarify the physical meaning of the Cp=0 isosurfaces in regard to being a drag source? I think you called it "red clouds". The reference pressure was 0 Pa and set at the outlet BC, I´m guessing? Best regards, Pedro
@AirShaper3 жыл бұрын
Hi Pedro, I use Cp-total in tje tutorial. That is the pressure coefficient calculated using the total pressure. If you make a 3D isosurface of that in the air (so not at the outlet boundary) you get a 3D surface that denotes the split between zones with a total pressure coefficient above and below zero. Everything contained within those clouds has a Cp-total lower than zero (so lower than the total pressure of the free stream). These low pressure 'bubbles' hold the vehicle back, as this negative pressure creates a suction effect on faces pointing towards the rear of the car in many areas.
@pedrobrito80803 жыл бұрын
@@AirShaper Thank you! I found the channel today and it has been very educational. The chats with real world designers are a great touch. Please keep producing content.
@AirShaper3 жыл бұрын
Thanks Pedro, will do, good luck to you!
@AirShaper3 жыл бұрын
@@pedrobrito8080 Thanks a lot! And good luck with your projects!
@Willy_LGM3 жыл бұрын
Is there any way we can download the sample files from this tutorial please?
@AirShaper3 жыл бұрын
Hi Willy, not for this model directly (although the Drivaer car can be requested at the TUM - Technical University of Munchen). I recommend using the simulation data of this public project instead: app.airshaper.com/projects/sample/sports-car Just click on the button "Simulation data" to download it - the structure is entirely the same as for this tutorial!
@ashok3052 жыл бұрын
hello, can we animate results..?? could you plz make a video thank you
@AirShaper2 жыл бұрын
Dear Ahsok, yes, I believe it is possible to make animations in paraview (changing camera positions and even having particles move along a trajectory?). We don't have enough experience on that ourselves to make a video, however. There is quite a large paraview community (with forum), perhaps you can find answers there!
@idreeskhan16293 жыл бұрын
Nice explanation,could you plz upload a vedio how to extract the data and from paraview and plot in gnuplot,how to compare the extracted data with some other results usin gnuplot.
@AirShaper3 жыл бұрын
Hi Idrees, such a video would be too specific / detailed for our channel. But I've exported data from curves for example to csv, to then plot in excel!
@idreeskhan16293 жыл бұрын
@@AirShaper where is that vedio?
@AirShaper3 жыл бұрын
@@idreeskhan1629 There is no video on that topic - it's just how I did it in the past. For example, you can first plot the surface data on an object and then make a 2D slice through it. That will give you a curve. Then, you can click that slice and go to "File - Save data" and save it as a csv file. You can then process that data in excel. You may need to first add coordinates to the results (using a calculator) so X, Y and Z are exported as well.
@idreeskhan16293 жыл бұрын
@@AirShaperthank you, kindly if you send me your email i will send you a paper whose graphs i need if you guide me how draw those graphs please,
@AirShaper3 жыл бұрын
@@idreeskhan1629 Hi Idrees, I can't go as far as to provide custom assistance for free for everyone. If you need assistance, you can contact me at wouter@airshaper.com for regular (paid) consultancy.
@saidtacuri9010 Жыл бұрын
Could you share the 3D file?, please 🙏
@Tom-hg9lw3 жыл бұрын
Can you share the model please?
@AirShaper3 жыл бұрын
This is a public model available for download here: www.mw.tum.de/en/aer/research-groups/automotive/drivaer/ Please note there are many different combinations possible (estate, fasteback, detailed or simple underfloor, ...). Good luck!