Learning Forum

[uconcorde]

Hi Amine,

I am trying to use ADJUST macro to get second derivatives of my converged velocity field, but I got all zero values. Here is the code and procedure I am using. Can you please help me to find any mistake I have?

 

# include "udf.h"

DEFINE_ADJUST(adjust_gradient,domain)

{

Thread *t;

cell_t c;

face_t f;

domain = Get_Domain(1);

thread_loop_c(t,domain)

{

   begin_c_loop(c,t)

   {

      C_UDSI(c,t,0) = C_DUDX(c,t); // calculate d2u/dx2

   }

   end_c_loop(c,t)

}

}

 

Procedure:

1) Open my .cas file

2) Interpreted udf

3) Open my converged .dat file

4) User defined -> Scalars -> 1 -> Solution Zones: all fluid zones; Flux Function: none; Unsteady Function: none

5) Solving -> deselect User Scalar 0

6) Run calculation for 1 time steps

7) Check contour plot of User Defined Scalar: all zero values.

 

Best,

David

[Rob]

I suspect the solver is clearing the gradient value before it's saved in the case. I'd have a look at UDM rather than UDS: there is a difference, and also check the options in the TUI  /solve/set/expert

As an aside, please don't post into old threads which are marked as "solved": we don't tend to check in those!