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-   -   Release injection each time step in Fluent 14 (http://www.cfd-online.com/Forums/fluent/108714-release-injection-each-time-step-fluent-14-a.html)

jfeg October 31, 2012 03:35

Release injection each time step in Fluent 14
 
Hello,
I'm solving unsteady flow with steady DPM particles. So, I'd like to set up injection to be released only once in each time-step (probably at beggining of time-step).

I could not find this settings, can give a hint ?
Thank you.
jfeg

vicarious November 1, 2012 11:29

You need to setup a boundary with pulsed on/off type injection?
You can write an UDF to define these type of boundary by using a step function.
You can use a simple SIN or COS to define that, for exmaple:
F(x) = |sin(pi*t/2)|;
The function produces 0 ,1 periodically with the progression of time =1,2,3,...
I have a code here specifically for on/off injection you can use:

************************************************** ******
#include "udf.h"
DEFINE_PROFILE(injection_pulsed_flux, thread, position)
{
face_t f;
real t = CURRENT_TIME;
int n;
real pi;
n = 1000000.*t/1.7;
pi = 1.570796;
begin_f_loop(f, thread)
{
F_PROFILE(f, thread, position) = 100.*fabs(sin(pi*n));
}
end_f_loop(f, thread)
}
************************************************** ****
You need to replace you own 1/(delta t) where I have underlined (mine was 1e-6). The F profile will generate a specific number and zero. The "100" could be replaced by your own case's value.

Hope it could help,
Best regards.

santhosh kumar k February 13, 2013 00:47

Dpm model
 
Hai sir/Madam

I am using fluent software for my dpm injections ina GDI engines.Using pressure swirl atomizer i got injectios in the form of V shape instaed of a circular shape in 3d model.Please tell me which parameter does it depend on it. and how to modify.

Thank u

Santhosh Kumar K:)


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