Re: [sparta-users] Boundary condition, pressure drops drasticaly around the outlet

[<geo...@dl...>]

Dear Vahid,


On first thought, it seems to have to do with the boundary layer and outflow condition: you have a supersonic outflow at xhi, but the boundary layer is not necessarily supersonic.

For smaller values of the accommodation coefficient you have (mostly) specular reflection, which given the relatively small angle of the body still retains enough velocity in the x direction to provide a supersonic flow in the slip layer.


Mit freundlichen Grüßen
Dr. Georgii Oblapenko
Postdoctoral Researcher
Alexander von Humboldt Stiftung Fellow
Institut für Aerodynamik und Strömungstechnik

Deutsches Zentrum für Luft- und Raumfahrt (DLR)

________________________________
From: Vahid Jafari <ja...@hs...>
Sent: 12 June 2023 12:57:47
To: spa...@li...
Subject: [sparta-users] Boundary condition, pressure drops drasticaly around the outlet


Deal all,



I am a Ph.D. student researcher at  Helmut-Schmidt university in Hamburg, working with SPARTA for hypersonic flow purposes. However, I am having some issues with the boundary condition at outlet. I have a 2d axisymmetric flow filed around a half body like in the picture below. We evaluate the data along the white line in the picture below.



[C:\Users\guest\Downloads\Compressed\23Peravali-Jafari\pictures][cid:168...@hs...]



The problem is that the pressure drops drastically (which is unrealistic) around the outlet as seen in the picture below.



[cid:168...@hs...]



It happens for an accommodation coefficient of 1. By decreasing the accommodation coefficient, this vanishes such that for an accommodation coefficient smaller than 0.2 it completely disappears.



[cid:168...@hs...]



Do you have an explanation for that or do I configure something wrong here. Enclosed you can also find the input files



Thank you for your help in advance.

Kind Regards,



Vahid Jafari



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