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    • Rahul Ponginan

      Please click here for a short but important announcement   03/26/17

      Dear Users Our Commercial and Academic users around the world can use these same forums here as before i.e. the Altair Support Forum , Commercial users from India with solver queries can go to the Solver Forum for India Commercial Users , Academic Users from India and AOC India Participants are requested to go to the Forum for India Academic Users and AOC India Participants , We will be tending to all queries in all the forums promptly as before, thank you for your understanding. 


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  1. Any ideas on how to view the shear rate? I've got a few other questions as well. I'm trying to get a viscoelastic flow through a pipe to work. It's a highly viscous HDPE and I've got some trouble getting it to stabilize at high inflow pressure values (10 bar and above). The job aborts with the following error: acuSolve: *** ASSERTION in Function <lesGmres> File <lesGmres.c> Line <1345> acuSolve: *** Error from fLesGetHbrgEig <26> acuRun: *** ERROR: error occurred executing acuSolve It runs at lower pressures like 1 bar, but that won't suffice for my case. I tried raising the Krylov vector count and lowering the time step considerably, but no luck so far. The viscoelastic residual ratio starts at 0.9 and drops to 0.5 which isn't great, but the other residual ratios as well as the solution ratios are ok. So what exactly is the cause of this instability? Following this, I wanted to stabilize it by using a multiplier function to raise the pressure or the inflow velocity linearly as I got the same *** ASSERTION error when trying to start a viscoelastic case using restart files from a purely viscous case. However, Acusolve does not seem to accept my implementation of a multiplier function. I attached the case - what's the error? time_01.rar
  2. Wonderful, thank you. However, the shear rate is not available with this option, either. Is there a possibility to view it? Also, I meant to post the topic in the Hyperview subforum initially. But while we're here, I've got another question: I'm using Acusolve 2017.1 locally and Acusolve 14 on a cluster and I've noticed a strange behaviour with version 14. When using the Phan-Thien Tanner or Giesekus viscoelasticity model, the fluid viscosity sometimes stays constant although the models predict a shear thinning behaviour. I know that setting a viscoelastic model overrides the use of any viscosity option like Carreau or Power law and setting them doesn't change anything, so this is very odd. I haven't been able to pinpoint the exact reason. Any ideas? Edit: Okay, I've found it. When using the AcuConsole GUI and defining a viscosity type like Carreau in the viscoelastic section of a fluid, it is not recognised! You have to set this in the viscosity section of the material, otherwise it is ignored. The same goes for the definition via inputfiles of course. Why is that?
  3. Hello all, I'm examining simulations of viscoelastic fluids with Acusolve 2017.1. When exporting the result files to EnSight to view them in Hyperview, I can't find the option to show the viscoelastic stresses, only the gradient. Also, I'd like to see the apparent fluid shear rate. How can one do this?
  4. Hi, sorry for the late reply, I forgot this topic. I want to simulate the flow of molten HDPE which exhibits slip between the fluid and the wall following a certain function depending on the wall shear stress. A simple BC won't do it for this type of BC since either slip or no slip are available as options and none of those satisfy the real behaviour close enough. If interested, you can take a look here: https://www.researchgate.net/publication/251585191_Slip_effects_in_HDPE_flows I got a reply from the Altair support team, it is possible to implement this using advanced options like tangential traction, although I don't know yet if it will be possible to use the way I need it to.
  5. Hello, I will soon study the behaviour of HDPE melt which exhibits slip at walls. A few questions arise regarding this, mainly and most importantly how to implement a wall function allowing slip following a certain law. I could not find an option to use a UDF for walls. Is this at all possible in Acusolve 2017.1? Modelling another property of HDPE (viscosity model dependent on pressure and temperature) seems to be possible without a problem using UDFs.
  6. Cannot toggle/merge some free edges

    Thank you very much, how did you do it exactly? I tried many different methods and cleanup tolerances, but a few edges refused to be corrected. Another issue is coming up when I try to create a CFD tetra mesh: after a while, the meshing process aborts displaying "All BL truncated" and "Tetra mesh failed, error= -1". The surface mesh of the jet body encloses a volume (no free edges). The mesh is rather coarse for testing purposes, but a finer mesh didn't make a difference. How do I resolve this? Also, the meshing algorithm tries to mesh the inside of the jet body. I tried a full body as well as a half, it didn't work either. suchoi.hm After a bit of mesh checking, I observed that the jet was still an enclosed body and that there were many squished elements. After a cleanup, it meshes just fine.
  7. Hi, I'm trying to mesh a jet fighter with Hypermesh 2017. The problem is that the model was a rendered model in .igs from grabcad and it wasn't intended to be meshed or simulated, but only for visual purposes. The model consisted solely of surfaces and it was a mess in general, the main problem being that the surfaces were not connected to each other. I've got pretty far with the preprocessing, but now I'd like to build the enclosure around it to create the fluid mesh and I'm struggling with the connectivity between the symmetry plane and the outer jet surfaces. Some edges refuse to be equivalenced, toggled or replaced and I can't create the fluid mesh. I created the cutout of the jet on the symmetry plane by projecting the lines to the surface and trimming it with them. Does anyone know how to connect the lines correctly? suchoi.hm
  8. I just tried to use COUP_KIN instead of KINCOUP and it works! I don't know why, but it does. For reference, my version is 14.0.110.
  9. I tried that and it persists within all my models. I think I don't define the coupling in HM properly since it's the only thing that does not work when imported. My workflow is as follows: 1. Create mesh 2. Create temporary node, move to set "refnode" 3. Create node set "loadset" to be coupled 4. Go to 1D → Rigids, elem type = KINCOUP. Independent = "refnode", dependent nodes = "loadset" 5. Move KINCOUP elements to collector "rigids" 6. Create solid property card for part with material card, assign property to solid and material to property 7. Create rigid property card, assign it to "rigids" collector, assign material to the property, under Elset options: Component name = "rigids" 8. Set temporary node "refnode" as reference node 9. Create CLOAD in load step browser, with node set = "refnode" I tried not assigning a material to the rigid property and I tried deleting the temporary node and assigning the created node from the rigids as reference node. No couping is imported into Abaqus. I don't see where the error is. Error: WARNING: Unknown assembly level element set RIGS. This occurred while processing rigid body definition. The rigid body definition will be ignored. WARNING: The following keywords/parameters are not yet supported by the input file reader: --------------------------------------------------------------------------------- *KINEMATICCOUPLING
  10. Hi, the sets are active. The boundary condition is imported properly into Abaqus. The only thing missing in Abaqus is the nodeset the concentrated force is applied on, which is odd.
  11. Hi again, it's been a while since I used Abaqus and I am facing the same issue. Abaqus tells me: The model "test" has been created. The part "PART-1" has been imported from the input file. WARNING: Unknown assembly level element set RIGIDS. This occurred while processing rigid body definition. The rigid body definition will be ignored. WARNING: The following keywords/parameters are not yet supported by the input file reader: --------------------------------------------------------------------------------- *KINEMATICCOUPLING The model "test" has been imported from an input file. Please scroll up to check for error and warning messages. When trying to run a job, the following pops up: The job "Job-1" has been created. The job input file "Job-1.inp" has been submitted for analysis. Error in job Job-1: NODE SET ASSEMBLY_LOADSET HAS NOT BEEN DEFINED Error in job Job-1: A CONCENTRATED LOAD HAS BEEN SPECIFIED ON NODE SET ASSEMBLY_LOADSET. THIS NODE SET IS NOT ACTIVE IN THE MODEL Job Job-1: Analysis Input File Processor aborted due to errors. Error in job Job-1: Analysis Input File Processor exited with an error. Job Job-1 aborted due to errors. So, why is the set not defined or exported from HM? Where's my error? HM version is 14, Abaqus version is 2017. test.inp test.hm
  12. I got Acusolve 2017 installed locally an a machine to test a few things. By the way, I went to an Acusolve training session a few months ago and we were told to pick fixed time stepping over adaptive time stepping. After asking why, since every other program I know supports adaptive time stepping without a problem, we were given no details unfortunately. Maybe this was the reason. Also, I just tried opening a test run of AS2017 in Hyperview 14 using the .log file after the same case done with adaptive and fixed time stepping. When I try to apply the velocity contour plot, Hyperview just crashes and closes without a message. Using Ensight is no problem.
  13. Hi again, I was wrong in my previous reply. The version installed on the cluster is 14.0 while my local version is still 13.0, so no wonder there might be compatibility issues. Sorry for that, no more searching needed I guess. I just tried H3D and while it did convert with AcuTrans without errors, Hyperview tells me this after a few messages: Error: Failed to attach results.
  14. There is only one version of Acusolve suite installed, which is v13.0
  15. Hi, Thanks for your answer. Acusim.dir exists of course. With the Reader Options tab, I did get all my output options to show up, but I still got the "Time does not match" error. Until now, it only occured when I ran shear thinning (power law) cases, newtonian setups were no problem. When this happens, the displayed time steps do not match the results I expect. For example, the case at hand was the full geometry I am examining and I already ran parts of it (1 degree, 5 degrees of the rotationally symmetric body), so I know what to expect. The last displayed result of the full body is not what the other cases showed, which I ran on my local machine and exported to Ensight using AcuOut. I just tried acuTrans. I opened Acusolve CMD prompt, navigated to my case and typed "acuTrans -translate_to ensight" to test it. Unfortunately, it told me this: acuTrans: *** ASSERTION in Function <iopCheckStr> File <iopLow.c> Line <2074> acuTrans: *** data out of order: expected <nAoutVecs> found <nFields> in binary file <ACUSIM.DIR/acusolve.2_0_x.out> token <8> near <nFields> Is the message "data out of order" maybe related to the issue I have described above? As far as I know, there is no GUI access.