i have some questions about hyperworks CFD

Kesit Bayu

Hi, my name is Kesit Bayu 

I have finished the CFD analysis, then I try to read the analysis results using the hypergraph, why does the hypergraph show the time variable? whether in this case is iteration? Is there any suggestion to read the analysis result from hyperworks cfd so that the reading is more accurate? I am also still confused in choosing the turbulence model. Any suggestions in this case?

thank you

Best Regards

acupro

It appears HyperGraph does not have the 'toggle' between step and time, it only plots time for the X-axis..

If you're using HyperWorks CFD, the 'Plot' utility (under the Solution ribbon, to the far right in the Simulation section) allows you to perform similar plotting functions, within the same HWCFD GUI.  It also gives you the choice for X-axis, time step or time.  There you can plot solution ratio, residual ratio, surface integrated values, etc.  You'll see several of the HyperWorks CFD tutorials include snippets of how to use this Plot utility.  I find the 'ACU-T: 5000 Blower - Steady (Rotating Frame)' tutorial under Moving Body useful, as it has an example of residual/solution ratio plots and integrated results on an Output Surface set.

AcuSolve provides a wide range of turbulence models.  Most models provide good solutions over a wide range of simulation types, but there are always those cases where one model might provide better comparisons to physical tests than another model.  The Spalart-Allmaras turbulence model works very well in AcuSolve, with all the latest published updates and corrections to that model, and is only one equation so is less expensive on runtime than a two-equation model.  If you want to use a K-Epsilon based model, the Realizable K-Epsilon model appears to be most robust across a range of simulations.  The choice of turbulence model and it's effect on the simulation results is yet another sensitivity study that users will undertake, in addition to mesh sensitivity, time step sensitivity, etc.

Kesit Bayu

acupro_21778 said:

It appears HyperGraph does not have the 'toggle' between step and time, it only plots time for the X-axis..

If you're using HyperWorks CFD, the 'Plot' utility (under the Solution ribbon, to the far right in the Simulation section) allows you to perform similar plotting functions, within the same HWCFD GUI.  It also gives you the choice for X-axis, time step or time.  There you can plot solution ratio, residual ratio, surface integrated values, etc.  You'll see several of the HyperWorks CFD tutorials include snippets of how to use this Plot utility.  I find the 'ACU-T: 5000 Blower - Steady (Rotating Frame)' tutorial under Moving Body useful, as it has an example of residual/solution ratio plots and integrated results on an Output Surface set.

AcuSolve provides a wide range of turbulence models.  Most models provide good solutions over a wide range of simulation types, but there are always those cases where one model might provide better comparisons to physical tests than another model.  The Spalart-Allmaras turbulence model works very well in AcuSolve, with all the latest published updates and corrections to that model, and is only one equation so is less expensive on runtime than a two-equation model.  If you want to use a K-Epsilon based model, the Realizable K-Epsilon model appears to be most robust across a range of simulations.  The choice of turbulence model and it's effect on the simulation results is yet another sensitivity study that users will undertake, in addition to mesh sensitivity, time step sensitivity, etc.

thanks for this answer sir, it is very helpfull, when i can find the tutorial ACU-T: 5000 Blower - Steady (Rotating Frame)? Is this tutorial on YouTube or in the Altair forum?

thanks 

best regards

kesit

acupro

Kesit Bayu said:

thanks for this answer sir, it is very helpfull, when i can find the tutorial ACU-T: 5000 Blower - Steady (Rotating Frame)? Is this tutorial on YouTube or in the Altair forum?

thanks 

best regards

kesit

From HyperWorks CFD, try File > Help > Tutorials

The inclusion may depend on which version you are using...

Kesit Bayu

acupro_21778 said:

From HyperWorks CFD, try File > Help > Tutorials

The inclusion may depend on which version you are using...

sorry sir, where I can find this folder? in this forum or in another web? 

acupro

Kesit Bayu said:

sorry sir, where I can find this folder? in this forum or in another web? 

From the thread topic, I'm assuming you're using HyperWorks CFD.  Upper-left corner:  File > Help > Tutorials, then you can browse through the topics for various tutorials.  That particular ACU-T: 5000 is under the 'Moving Body' set.

Kesit Bayu

acupro_21778 said:

From the thread topic, I'm assuming you're using HyperWorks CFD.  Upper-left corner:  File > Help > Tutorials, then you can browse through the topics for various tutorials.  That particular ACU-T: 5000 is under the 'Moving Body' set.

thanks for the answer sir, it is very helpful, I will try it

 

Kesit Bayu

acupro_21778 said:

From the thread topic, I'm assuming you're using HyperWorks CFD.  Upper-left corner:  File > Help > Tutorials, then you can browse through the topics for various tutorials.  That particular ACU-T: 5000 is under the 'Moving Body' set.

sorry sir, can i ask again, the time step here does it show the position or is there a time variable? I am quite confused in understanding it, because I am doing static analysis, I have used the acuprobe as in the tutorial

acupro

Kesit Bayu said:

sorry sir, can i ask again, the time step here does it show the position or is there a time variable? I am quite confused in understanding it, because I am doing static analysis, I have used the acuprobe as in the tutorial

For a steady-state/static analysis, AcuSolve still uses time steps (for the outer loop of the solvers) but the time increment is very large - on the order of 1E+10.  We are not interested in a time-accurate process to get to the final solution - only in the final solution, so the time integrator is only first order.  We are not seeking a physical, converged solution at each time step - only by the end solution.  Only the solution at the end would be considered the actual solution.

When we switch to a transient analysis, we use a more physical time step size, and the time integrator is second order, because we want each time step to reach a physical, converged solution.

Kesit Bayu

acupro_21778 said:

For a steady-state/static analysis, AcuSolve still uses time steps (for the outer loop of the solvers) but the time increment is very large - on the order of 1E+10.  We are not interested in a time-accurate process to get to the final solution - only in the final solution, so the time integrator is only first order.  We are not seeking a physical, converged solution at each time step - only by the end solution.  Only the solution at the end would be considered the actual solution.

When we switch to a transient analysis, we use a more physical time step size, and the time integrator is second order, because we want each time step to reach a physical, converged solution.

thanks for your answer sir, it is very helfull for finish my project