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Yatish Chandra

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  1. @raskolnikov I used my CAD file to determine the cartesian co-ordinates for the center of rotation and then used that in AcuConsole. I think that is the easiest way. It was basically the center point on the fan hub which was used as the point of rotation. There is a way to do it on AcuConsole too. You can right click on 'Models' > Query > and then use some of the options there to figure out the center of rotation. I hope this answers your query.
  2. @raskolnikov You'll have to calculate the components of rotation for the different axis using = RPM*cos(Angle) as explained above. Then, based on the orientation of the axes, make sure you specify the correct sign conventions, which is really important. In my case, based on the figures attached above, the components were somewhat as follows: x: RPM*cos(Angle) y: 0.0 z: -(RPM*cos(Angle)). The -ve sign for the z component made all the difference.
  3. @acupro Thanks for your valuable insights and recommendations. It looks like I had to use a -ve sign for the Z-component as you have mentioned. That fixed the rotation issue I have been facing.
  4. Thanks for the info @acupro. So I have tried to simulate simplified models by isolating the fans to better understand the rotation and I still seem to have some issues. I have attached the velocity magnitude contours on the surface of a standard fan and a fan with an inclined axis. As you can see, the contour on the standard (non inclined fan) makes sense wherein the magnitude increases from the hub to the tip. Whereas with the inclined fan, that is not the case. I have used the same boundary conditions for both the cases and for the inclined fan, I calculated the Angular Velocity components as follows: The fan makes an angle of 40 degrees with the x axis and 50 degrees with the global z axis. X component: RPM*cos(40 deg) = 4000*cos(40 deg) Y component: 0 (rotation about y axis) Z component: RPM*cos(50 deg) = 4000*cos(50 deg) I have tried several other approaches, for example RPM/cos 40 and RPM/cos50 however, the rotation still doesn't occur about the right axis. I would appreciate any help on how to fix this issue. I have been stuck with this for over a week now. Thanks, Yatish
  5. Thanks for the inputs @ydigit and @acupro . I just want to clarify that I have the right understanding. If the rotation axis of the fan makes an angle of 58 degrees with the global x axis and 32 degrees about the z axis (inclined about y axis as seen in last figure), will the angular velocity components in that case be as follows?: X Component: RPM*cos(58) Y Component: 0 Z-Component: RPM*sin(32) Thanks, Yatish
  6. Hello everyone, I am trying to simulate axial fans located behind the radiator of a semi truck in AcuConsole. I have three sets of fans in which one set has its axis similar to global coordinate system whereas the other two sets of fans have their rotation axis inclined to the global coordinate axis. I have tried to run the simulation but I have been experiencing divergence issues. I figured out the reason for this and it appears to be with the axis of rotation of the inclined set of fans. Till now, I have been creating a reference frame where i specify the rotation center as the center of rotation for the fan and then specify the RPM using the angular velocity option along one component (X, Y or Z). This I think is wrong. Could somebody help me out with specifying the correct axis of rotation for the inclined set of fans? Should I specify different X, Y & Z components in the angular velocity section of the reference frame for the fans or should I change the 'Wall Velocity type' to 'Cylindrical' in the 'surfaces' tab, specify the cylindrical axis in AcuConsole? In that case, I was wondering if I should keep the Radial. Axial & Tangential velocity sections to 0.0 m/sec or give them a value? I have attached some screenshots which may help for reference. Thanks, Yatish.
  7. Thanks for the input @acupro . I'll try to reduce the mesh count and try it again.
  8. Hello everyone, I am currently simulating an entire truck assembly in a wind tunnel environment using the AcuConsole pre processor and AcuSolve solver. I have around three porous mediums in my model along with 18 axial fans (Rotating reference frames) which has blown up the overall element size and also the complexity of the model. When I try to run the model setup in AcuSolve, after the domain has been decomposed, I get the following errors: acuRun: Run acuSolve ... acuRun: set KMP_AFFINITY=scatter acuRun: set MP_SET_NUMTHREADS=72 acuRun: set OMP_NUM_THREADS=72 acuRun: set OMP_DYNAMIC=FALSE acuRun: set MPC_GANG=OFF acuRun: "C:/Program Files/Altair/2017/acusolve/win64/bin/acuSolve".exe -np 1 -nt 72 acuSolve: AcuSolve checked out license from HyperWorks acuSolve: *** ASSERTION in Function <memAlloc> File <mem.c> Line <129> acuSolve: *** Unable to allocate <290044352> bytes; already allocated <73318612992>; from file <topSd.c> line <1451> acuRun: *** ERROR: error occurred executing acuSolve" acuRun: Wed Apr 4 16:07:48 2018 I have tried to change the mesh size and restart my computer but nothing seems to fix this issue. Could anyone provide more insight into this issue? I am also attaching the log file for reference. From what I can understand, it looks like a problem with my workstation not having sufficient memory to run the analysis. I am running it on a 36 Core (72 logical processors), 64 GB machine. Thanks, Yatish AssemFan.3.Log_acuTail.txt
  9. Hello everyone. I am currently running external aerodynamics flow simulations for a truck model. I use HyperMesh to generate the surface mesh and then use Virtual Wind Tunnel to run the flow simulation. Once the simulation is complete, VWT generates the automatic PDF report with a drag coefficient value. However, after performing design modifications to the geometry of the model, the drag coefficient values seem to be off from expectations. Hence, I am wondering if there is a way to manually calculate the drag force generated by the model in AcuFieldView, AcuConsole or AcuProbe and then the drag coefficient using the frontal area?. I want to check the validity of the drag coefficient values that are automatically generated in the report. Also, I have noticed that the report calculates the drag for each and every part in the model and then sums it up to give the total drag value. I'm wondering if there is a way to select the entire model (all parts included) and display the drag force created by it rather than doing it for individual parts. Thanks for the help in advance! Yatish Chandra
  10. Thanks for the input ydigit! I was able to locate the problem areas in HyperMesh and run the analysis in VWT.
  11. Hello, I am conducting an external aerodynamic analysis of a semi truck using VWT. I am currently facing issues within the VWT. I have created a surface mesh using HyperMesh and have checked and fixed for any bad elements. The 2D mesh check for Tetramesh tells me that the "Mesh is OK for Tetramesh" and after that, I am able to export the .nas file successfully onto VWT. However, when I run the analysis, the Volume mesher keeps failing for some reason. I have attached the error file and screenshots of the VWT run folder. Could you please help me point out what the issue currently could be? P.S: The files are from three different runs vwtAnalysis.1.MeshSim.txt vwtAnalysis.1.MeshSim.txt vwtAnalysis.1.MeshSim.txt
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