[hobing]

hi all,
how can i do plot to energy spectrum

"""
TKE = 0.5 * (RMS u^2 + RMS v^2 RMS w^2) + SGS K

SGS K = Nu_sgs /rho *L_sgs
(rho = global density,
Nu_sgs = dynamic viscosity in subgrid scale )
L_sgs = min (kappa*d*C_s*delta)
(kappa = Von Karman const.
d = wall distance
C_s = Smagorinsky const.
delta = filter size = (cell volume ^(1/3))
"""

This is what I found. But I heard that CFF(custum field function) can calculate TKE in fluent.
It's difficult. Is there a way?

I also thought about UDFs

"""
#include "udf.h"

DEFINE_ON_DEMAND(cal_k_subgrid)
{
Domain *d; /* declare domain pointer since it is not passed as an
argument to the DEFINE macro */
Thread *t;
cell_t c;

d = Get_Domain(1);

#if !RP_HOST /*Serial or on nodes*/

thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
real L_sgs = Compute_L_sgs(C_VOLUME(c,t),C_WALL_DIST(c,t),C_Cen troid_Y(c,t));
C_UDMI(c,t,0) = SQR(C_MU_T(c,t)/(L_sgs*C_R(c,t) + SMALL));
}
end_c_loop(c,t)
}
#endif /*!RP_HOST*/
}
"""

It's a UDF code I found somewhere ("https://www.eureka.im/900.html"), but an error occurs in the part defined by 'Compute_L_sgs'
Can you tell me about that function?


I am trying to post-process FFT after calculating TKE with UDF or CFF.
please suggest a way
please..