[sreekargomatam]

I use a nonlinear k-e model and the Reynolds Stress is stored in the User defined memory. Is it possible to clear that user defined memory after a set number of iterations while running the case??

[ComputerGuy]

Sure. Is it a transient case or a steady-state case? The define_adjust macro will run once per iteration, and thus you'd need to simply hook your reset macro (with appropriate logic) into define_adjust.

I haven't tried the code below, but it should give you an idea of what to do.

#include "udf.h"
int IterCounter=1;

DEFINE_ADJUST(adjust_fcn,d)
{
	Thread *t;
	cell_t c;
	/*reset if iterations > 2000 */
	if(IterCounter>2000)
	{
		IterCounter=0;
		thread_loop_c(t,d)
		{
			if (FLUID_THREAD_P(t))
			{
			begin_c_loop_all(c,t)
				{		
					for (i = 0; i < n_udm; i++)
					{
						/*This loops over all UDM locations and resets them to 0.*/
						/* Implement your own values or logic here*/
						C_UDMI(c, t, i) = 0.0; 
					}
				}
			end_c_loop_all(c,t)
			}
		}
	}
	IterCounter=IterCounter+1;
}

ComputerGuy

[sreekargomatam]

Thanks for the code. It's a transient code. Will it make any difference if it's a steady case? If so, how?

[ComputerGuy]

I asked because doing something based on iterations in a transient code doesn't make a lot of sense (while they're correlated with flow time, it's not a fixed relationship, and you'd be resetting at random intervals). By iterations, do you mean time step?

ComputerGuy

Originally Posted by sreekargomatam

Thanks for the code. It's a transient code. Will it make any difference if it's a steady case? If so, how?

[sreekargomatam]

Yes. By iterations I mean the time steps. Is it possible to delete that data at the completion of a case. If I'm running the case for 100seconds, is there someway to delete the user defined memory after 100s from the data file?

[ComputerGuy]

Yes. The simple fix to the code below should clear the UDM after 100 seconds. It's a define on demand to prevent running every iteration for flow times beyond 100s

#include "udf.h"


DEFINE_ON_DEMAND(eraseudm)
{
	Thread *t;
        Domain *d;
	cell_t c;
        real current_time;
        current_time = CURRENT_TIME;
        d = Get_Domain(1);
	if(current_time>100)
	{
		IterCounter=0;
		thread_loop_c(t,d)
		{
			if (FLUID_THREAD_P(t))
			{
			begin_c_loop_all(c,t)
				{		
					for (i = 0; i < n_udm; i++)
					{
						/*This loops over all UDM locations and resets them to 0.*/
						/* Implement your own values or logic here*/
						C_UDMI(c, t, i) = 0.0; 
					}
				}
			end_c_loop_all(c,t)
			}
		}
	}

}

ComputerGuy

Originally Posted by sreekargomatam

Yes. By iterations I mean the time steps. Is it possible to delete that data at the completion of a case. If I'm running the case for 100seconds, is there someway to delete the user defined memory after 100s from the data file?

[moun139]

this is my udf to calculate gradient of temperature dt/dy,it write me error fluent reveice .....()

what's wrong ?


#include "udf.h"

DEFINE_ON_DEMAND(store_grad)
{
Domain* d;
Thread *t;
cell_t c;

d=Get_Domain(1);
thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_UDMI(c,t,0)=C_T_G(c,t)[1];
}
end_c_loop(c,t)
}
}
thx

[Amir]

Originally Posted by moun139

this is my udf to calculate gradient of temperature dt/dy,it write me error fluent reveice .....()

what's wrong ?


#include "udf.h"

DEFINE_ON_DEMAND(store_grad)
{
Domain* d;
Thread *t;
cell_t c;

d=Get_Domain(1);
thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_UDMI(c,t,0)=C_T_G(c,t)[1];
}
end_c_loop(c,t)
}
}
thx

Hi,

Did you patch the UDM before use?