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-   -   Setting up the pressure variation due to tornado in a duct(UDF)+animation (https://www.cfd-online.com/Forums/fluent/130728-setting-up-pressure-variation-due-tornado-duct-udf-animation.html)

 guillaume1990 March 3, 2014 12:59

Setting up the pressure variation due to tornado in a duct(UDF)+animation

Hello everybody!

I need your help if possible. For a project, I have to set the pressure variation due to tornado at the entrance of a duct and observe how far the pressure variation disappears. The problem is I don't understand the results for Contour Static Pressure because I don't see the pressure variation. Moreover, the animation video for static pressure doesn't work. So, I would like to know if you have any suggestion according to what I have done.

I explain each step to be sure I haven’t done any mistakes.

By Workbench:
Geometry:
Rectangular duct-3D: 500 * 500 * 2000 mm Body: Fluid
Mesh:
Outline view->Detail view->Sizing: Use Advanced Size Function set to On: Curvature and Use automatic Tet Inflation set to Program Controlled ->Update Mesh
Fluent:
*General:
-Scale: mm
-Pressure-Based; Time Transient
*Model:
-Energy Off
-Viscous- Standard k-e, Standard Wall Fn
*Material:
air-aluminum
*Boundary Condition:
-Operating condition-> Operating pressure: 0 Pa
-Pressure-inlet: Code UDF for Pressure total Intensity and Hydraulic Diameter: 10% and 500mm. For the pressure variation, I considered that the input pressure is 101325 Pa during 10 seconds then it decreases to 98325 Pa and rises again to 101 325 Pa. This variation lasts 10 seconds. I have put the following code UDF:
#include "udf.h"
DEFINE_PROFILE(pressure_magnitude, t, i)
{
real pressure_mag;
real the_current_time;
face_t f;

the_current_time = CURRENT_TIME;

if ((the_current_time>=0.0) && (the_current_time<10.))
{
pressure_mag=101325.0;
}
if ((the_current_time>=10.0) && (the_current_time<20.0))
{
pressure_mag=125.17*the_current_time*the_current_t ime-3755.2*the_current_time+126628.0;
}
if ((the_current_time>=20.0))
{
pressure_mag=101325.0;
}

begin_f_loop(f,t)
{
F_PROFILE(f,t,i) = pressure_mag;
}
end_f_loop(f,t)
}
-wall
-pressure-outlet: 101325 Pa
*Solution Method:
Non-iterative Time Advancement enabled->Scheme: Fractional Step
*Solution initialization:
Compute from pressure-inlet
*Calculation activities:
-autosave every (time steps): 1 and when the data File is saved, save the case: each time. Append File Name with Time-step
-Create/Edit Solution Animation:
Animation Sequences: 3 because I am not sure what pressure I have to observe. Active Name: Static Pressure When: Time Step, Define->Contours (window 4) Clip to Range enabled. Same thing for Total pressure (window 5) and dynamic pressure (window 6)
*Run Calculation:
-Time Step Size 0.2 s
-Number of Time Steps: 150 because the cycle lasts about 20s. 10 s with 101325 Pa for pressure inlet and 10 s of pressure variation due to tornado.
->Run
*Graphic Animation:
-Option: Double Buffering enabled
-Set Active Window to 4-> Apply
-Solution animation Playback->set up. Window 4 active. Static Pressure selected. Nothing is happening when I click on the play button...

So, I would like to know if I have done some mistakes in the steps? I hope it’s not too long to read.
It would be awesome if you have any solution to observe the animation of static pressure for example or if you have any suggestion to observe the pressure variation of tornado and see how far it disappears in a duct.
Thank you very much.

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