Search found 36 matches

by Christopher
Mon Jan 17, 2022 10:11 am
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hello everyone, finally I have done another mesh refinement in the free jet area under the nozzle. The deviation to the measured value is getting smaller and smaller. For illustration I have attached a diagram. You can see the curve from the simulation and the experiment. For better comparison, the ...
by Christopher
Wed Jan 05, 2022 9:22 am
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hello, as announced I have done a calculation run on a single operating point of our nozzle. You can see three different curves of velocity and temperature below the nozzle tip. They are the experimental data, the calculation data with the perfect gas model and the calculation data with the stiffend...
by Christopher
Wed Dec 22, 2021 12:14 pm
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hi Yvan, so far I can say that your cs_user_params works. I can't see any negative pressure. The difference between cp and cv is just the isentropic exponent k. Next I will compare the calculation results with our experimental results. I will make two runs. One with the stiffend gas model and anothe...
by Christopher
Tue Nov 30, 2021 12:42 pm
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hi Yvan,

alright. So to do it right, I have to replace the old (original) mesh with the new one under the mesh menu and then place a link to the old mesh under restart => different mesh, right?

Kind regards,
Christopher
by Christopher
Tue Nov 30, 2021 9:11 am
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hello Yvan, so far, I tried the computation restart. It works. I can go above 1.500.000 steps by splitting the caluculation in parts with checkpoints at each ends. However, one more question. I wanted to start the calculation with a coarse mesh for 600,000 iterations and a larger time step and then ...
by Christopher
Wed Nov 24, 2021 9:33 am
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hi Yvan, I will try that as well and inform you about the results. So far, I haven't tried a computation restart. Might be a good idea to calculate to 1.000.000 steps and then restart from there to continue. Unfortunatly, I can't increase the reference time step because of negativ energy encountered...
by Christopher
Mon Nov 22, 2021 9:32 am
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hi Yvan, thank you. Right now a calculation is running. After that I will give it a try. By the way, is there a limit to the calculation steps in CS7.1? I am running a compressible hot air flow simulation on a locally very refined mesh (smallest mesh size = 0,1 mm). With a max CFL <= 0,4, the achiev...
by Christopher
Thu Nov 18, 2021 12:56 pm
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hi Yvan,

anything new from this side?

Kind regards,
Christopher
by Christopher
Wed Sep 29, 2021 10:13 am
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hi Yvan,

I struggle where to set cv0. In the user parameters won't work. Could give a hint?

Kind regards,
Christopher
by Christopher
Mon Sep 27, 2021 8:15 am
Forum: code_saturne usage
Topic: Underestimation of velocity, compressible model
Replies: 31
Views: 16099

Re: Underestimation of velocity, compressible model

Hi, I have checked the setup.log file. The physical properties are defined as follows: gravity vector: [0, 0, 0] icorio: 0 (ignore Coriolis source terms) Continuous phase: ro0: 1.17862e+00 (Reference density) viscl0: 1.83000e-05 (Ref. molecular dyn. visc.) cp0: 1.00500e+03 (Ref. specific heat) icp: ...