We noticed that the turbulent viscosity for the detached eddy simulation is determined purely on the RANS model: S-A. This gives issues for simulating a single jet flow as it is unable to capture kelvin-helmholtz instabilities. After careful research, it was found that the turbulent viscosity in the free-mixing regions is about 50 times higher than for a purely large eddy simulation (LES). In order to overcome this issue we are seeking to replace the turbulent viscosity with a UDF that utilizes the SA turbulent viscosity definition when TKE DIS multiplier is < 0.9 (close to the wall) and converts to the Smagorinsky turbulent viscosity formulation otherwise. Our interpreted UDF is formulated as follows:<\/p>\n
———————————————-<\/p>\n
#include “udf.h”
#include “dpm_tools.h”<\/p>\n
DEFINE_TURBULENT_VISCOSITY(mix_visc, c, t)
{
real nu_ratio, tke_diss_mult, mu_t;
real cv_volume, c_str_mg;<\/p>\n
nu_ratio = C_R(c,t) \/ C_MU_L(c,t);
tke_diss_mult = C_UDMI(c, t, 22);
cv_volume = C_VOLUME(c,t);
c_str_mg = C_STRAIN_RATE_MAG(c, t);
if (tke_diss_mult > 0.9)
{
mu_t = 0.012*pow(cv_volume, 0.66667)*c_str_mg;
}
else
{
mu_t = 1.2*nu_ratio\/0.0000155*pow(nu_ratio, 3)\/(pow(nu_ratio, 3) + 7.1);
}<\/p>\n
return mu_t;
}<\/p>\n
——————————————<\/p>\n
And is generating the following errors when attempting to run it (8 cores Windows 11):<\/p>\n
==============================================================================<\/p>\n
Node 6: Process 12700: Received signal SIGSEGV.<\/p>\n
==============================================================================<\/p>\n
==============================================================================<\/p>\n
Node 3: Process 15496: Received signal SIGSEGV.<\/p>\n
==============================================================================<\/p>\n
==============================================================================<\/p>\n
Node 4: Process 22168: Received signal SIGSEGV.<\/p>\n
==============================================================================<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed: No such file or directory<\/p>\n
999999: mpt_accept: error: accept failed:<\/p>\n
===================================================================================<\/p>\n
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES<\/p>\n
= RANK 0 PID 15472 RUNNING AT KHLT01<\/p>\n
= EXIT STATUS: -1 (ffffffff)<\/p>\n
===================================================================================<\/p>\n
===================================================================================<\/p>\n
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES<\/p>\n
= RANK 1 PID 7268 RUNNING AT KHLT01<\/p>\n
= EXIT STATUS: -1 (ffffffff)<\/p>\n
===================================================================================<\/p>\n
===================================================================================<\/p>\n
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES<\/p>\n
= RANK 2 PID 17460 RUNNING AT KHLT01<\/p>\n
= EXIT STATUS: -1 (ffffffff)<\/p>\n
===================================================================================<\/p>\n
===================================================================================<\/p>\n
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES<\/p>\n
= RANK 4 PID 22168 RUNNING AT KHLT01<\/p>\n
= EXIT STATUS: -1 (ffffffff)<\/p>\n
===================================================================================<\/p>\n
===================================================================================<\/p>\n
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES<\/p>\n
= RANK 5 PID 23452 RUNNING AT KHLT01<\/p>\n
= EXIT STATUS: -1 (ffffffff)<\/p>\n
===================================================================================<\/p>\n
===================================================================================<\/p>\n
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES<\/p>\n
= RANK 7 PID 19944 RUNNING AT KHLT01<\/p>\n
= EXIT STATUS: -1 (ffffffff)<\/p>\n
===================================================================================<\/p>\n
The fl process could not be started.<\/p>\n
There is no further error message given in the generated error file. We suspect that there is an error in the formulated UDF, is someone able to identify the issue? we would appreciate it greatly!<\/p>\n
<\/p>\n","protected":false},"template":"","class_list":["post-283819","topic","type-topic","status-closed","hentry","topic-tag-fluent","topic-tag-fluid","topic-tag-udf-viscosity-model","topic-tag-user-defined-function-1"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t