999999.mpt accept :error :accept failed: invalid argument

- December 10, 2019 at 12:58 pm
  
  Bart
  Subscriber
  
  An error appears during the calculation. (SST K-W, UDRGM, Transient, V19.2)
- December 10, 2019 at 3:10 pm
  
  Rob
  Ansys Employee
  
  And if you restart Fluent what happens? What changes when the time step updates?
- December 11, 2019 at 5:56 am
  
  Bart
  Subscriber
  
  The same error happened, even I tried to reboot the computer. Decreasing the time step size also cannot solve this problem, and i use the fixed time step size. As the time updated, the error occurred and I couldn't review the results.
  
  Kind regards.
- December 11, 2019 at 8:38 am
  
  DrAmine
  Ansys Employee
  
  Can you make test with 0 as number of parallel processes?
- December 11, 2019 at 10:01 am
  
  Bart
  Subscriber
  
  It didn't work.
- December 11, 2019 at 4:34 pm
  
  Rob
  Ansys Employee
  
  It looks like the real gas model is trying to calculate density for 1 Pa: that's not going to be stable. Have a very careful look at the mesh & model settings and (as a test) try with fixed density then ideal gas and see what happens.
- December 12, 2019 at 6:00 am
  
  Bart
  Subscriber
  
  In this UDRGM, the energy equation is deactivated. If I write a UDRGM according to ANSYS help documentation, what I should change are "double RKEOS_density", "double RKEOS_speed_of_sound", "double RKEOS_viscosity" and "double RKEOS_rho_p" and the others remain unchanged.
  
  Is this right?
- December 12, 2019 at 6:18 am
  
  DrAmine
  Ansys Employee
  
  You need to provide consistent material properties. My question why you need for the udrgm?
- December 12, 2019 at 8:21 am
  
  Bart
  Subscriber
  
  If i don't need the energy equation, can i use the same properties (specific_heat, enthalpy and so on) according to UDRGM example in ANSYS help documentation? Therefore, I just change the material properties (density, speed of sound and viscosity) which are temperature-independent.
  
  Sir, you suggested me to use UDRGM according to my previous disscussion.
  
  Kind regards.
- December 13, 2019 at 12:12 am
  
  Bart
  Subscriber
  
  If that, can the material properties (rho_p) neglect or return 0.0 ?
- December 13, 2019 at 6:17 am
  
  DrAmine
  Ansys Employee
  
  I would say provide all input required by udrgm. You can provide whatever you want even independent of temperature.
  You can make a test if you are not sure about switching off equation via using the examples in the manual in dummy case and turning off equation if energy
- December 14, 2019 at 4:58 am
  
  Bart
  Subscriber
  
  Thank you for your reply! I will try this. @abenhadj
  
  Moreover, I tried to set a very small time step size, and increased the value of pre-sweeps of scalar parameters and coupled parameters to 1. The error disappeared and the calculation could be stable for a long time. However, the warning "absolute pressure limited to 1.000000e+00 in 1054 cells on zone 8" always existed. I am not sure whether this warning will affect the accuracy. @rwoolhou @abenhadj
  
  Kind regards.
- December 16, 2019 at 11:56 am
  
  Rob
  Ansys Employee
  
  If you have pressure based properties having cells capped at 1Pa (ie near enough vacuum) is going to effect the result and needs sorting out.
- December 17, 2019 at 2:11 am
  
  Bart
  Subscriber
  
  I found that the grids whose pressure were 1 Pa were adjacent to the wall and mostly located in the boundary layer. Does this mean to correction the wall fuction or the turbulent viscosity?
- December 17, 2019 at 6:18 am
  
  DrAmine
  Ansys Employee
  
  Have you done the test I suggested?

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