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-   -   UDS flux through wall and interior face. (http://www.cfd-online.com/Forums/fluent/41845-uds-flux-through-wall-interior-face.html)

shuqin July 26, 2006 03:07

UDS flux through wall and interior face.
 
Hi,Everybody.

I am modeling a UDS through two fluid zone,between them is a interior face,and I specify zero to UDS value at the top wall bundary ,and a non-zero flux to the bottom wall.

problems come when I use the following code to calculate UDS flux through each wall:

........................

c0 = F_C0(f, tf);

tc0 = THREAD_T0(tf);

F_AREA(area, f, tf);

uds_diff_ap=C_UDSI_DIFF(c0,tc0,0);

BOUNDARY_FACE_GEOMETRY(f,tf,A,ds,es,A_by_es,dr0);

if( THREAD_STORAGE(tf,SV_UDS_I(0)) != NULL )

diff_flux += NV_MAG(area)*uds_diff_ap*(F_UDSI(f,tf,0)- C_UDSI (c0,tc0,0))/ds*A_by_es;

...................

I thought I specified boundary values and there should be UDF flux through the wall,but I got zero flux,someone know the reason?

and I also use

face_value0 = C_UDSI(c0,tc0,0)+NV_DOT(C_UDSI_G(c0,tc0, 0),dr0);

face_value1 = C_UDSI(c1,tc1,0)+NV_DOT(C_UDSI_G(c1,tc1, 0),dr1);

to calculate the interior face value,it turned out face_value0 differs from face_value1,and suggestions?

RoM July 26, 2006 05:40

Re: UDS flux through wall and interior face.
 
Does fluent calculate any uds flux? You can use //report/uds-flow to get the uds flow rates at boundraries.

The difference between the two face vaules is usual for FVM based codes. If you need the face value you can use (face_value0+face_value1)/2 as a first estimate.

RoM

shuqin July 29, 2006 03:54

Re: UDS flux through wall and interior face.
 
yes Rom,you are ture,Fluent does not calculate any uds flux.

my intention was to made some modifacation with UDF to make sure that at the interior face the uds flux from zone 1 equals the flux into zone 2,however fluent deal different zone interface(specified as interior) with node value and approximation(zone 1 and zone 2 specified with different uds diffusivities),this thus cause the flux into through the interface extreamly big,how should I elimite this gradiant effect?

about the zero flux from the top wall and the bottom wall ,it is due to the print presion set in pritf(),and it is not zero.


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