# Problem in Species Transport in SU2

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 October 23, 2023, 04:35 Problem in Species Transport in SU2 #1 New Member   Syed Mafooq Ul Hassan Join Date: Jul 2023 Posts: 3 Rep Power: 2 Hi, I am new to CFD simulations. The species that I want to transport circles around the inlet and doesn't move towards the outlet. Attached, please find my configuration file and inlet.dat file. config.txt inlet_m.txt Any help or suggestion is highly appreciated.

 October 24, 2023, 16:51 #2 Senior Member   bigfoot Join Date: Dec 2011 Location: Netherlands Posts: 531 Rep Power: 17 It's a bit hard to say without the mesh to reproduce the issue, but you could first try to run it : 1. steady 2. with uniform boundary conditions instead of a profile When in doubt, start from something that works, either a tutorial or one of the regression tests in Testcases/ and build up your case step by step.

November 29, 2023, 17:07
#3
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Join Date: Feb 2022
Posts: 18
Rep Power: 4
Quote:
 Originally Posted by HassanGill Hi, I am new to CFD simulations. The species that I want to transport circles around the inlet and doesn't move towards the outlet. Attached, please find my configuration file and inlet.dat file. Attachment 96820 Attachment 96821 Any help or suggestion is highly appreciated.
Hi Hassan,

Are you simulating air or other gas? given your setup, it seems that you are simulating air, so if that is the case, you should check your value of the diffusivity
KIND_SCALAR_MODEL= SPECIES_TRANSPORT
DIFFUSIVITY_MODEL= CONSTANT_DIFFUSIVITY
DIFFUSIVITY_CONSTANT= 1

1 looks quite high, the diffusivity constant should be a value around 1.8*10^-5 , so now you are using a huge value, that might explain why the species does not move towards the outlet, because the diffusivity term is too high. Also as an advice, it is recomended to set the SPECIES_INIT equal to the species mass fraction that you provide in the first inlet (0.5 if I am not mistaken) because that improves the convergence.
SPECIES_INIT= 0.5
SPECIES_CLIPPING= YES
SPECIES_CLIPPING_MIN= 0.2
SPECIES_CLIPPING_MAX= 1.0

Finally, the
MARKER_INLET= (inlet, 300, 1.0, 10.0, 10.0, 0.0)

(10,10,0.0) should be the normal direction of the velocity, the second value 1.0 is the magnitude of the velocity, so if your velocity is 10 m/s, you should write the marker_inlet as follows:
MARKER_INLET= (inlet, 300, 10.0, 1.0, 1.0, 0.0)
and the INC_VELOCITY_INIT= ( 10.00, 0.0, 0.0 )

Best regards,

Cristopher Morales Ubal

 Tags #cfd, #species_transport, #su2