Mismatch of mass flow rates after source term implementation in SU2

akshaydeshpande · August 2, 2016, 13:33

Hi SU2 users,

I have implemented a source term of dissipative heating in SU2 v. 4.2.0. The expression for the source term is $S = \frac{Q}{\pi^{3/2}.a.b.c} e^{(-((x-x_{o})/a)^{2} - ((y-y_{o})/b)^{2} - ((z-z_{o})/c)^{2})}$
The total power deposited is $Q = \iiint_{-\infty}^{\infty} Sdxdydz$

To test the implementation, I am running a simple source in a 2D rectangular box case. The calculations are in dimensional form. The B.C's I am using are :
MARKER_SUPERSONIC_INLET at the inlet
MARKER_SUPERSONIC_OUTLET at the outlet
MARKER_FAR at the top and bottom edges
The location of the source is at $(x_{o}, y_{o}) = (1.5, 0.5)$ ,

and

I am getting the expected flow-field but the mass flow rates are not matching at the inlet and the outlet and therefore the energy balance is not working out. I have tried using both the Residual as well as Cauchy convergence criteria. For the later, I used CAUCHY_FUNC_FLOW as MASS_FLOW_RATE with maximum permissible CAUCHY_ELEMS corresponding to unsigned short datatype - but the result is still incorrect. I have also tried increasing the length of the domain.

Please let me know if there is any other way to run the calculation for a longer time to achieve convergence or if my implementation of the source term is incorrect.

I have attached the results below.

Thanks in advance!

akshaydeshpande · August 12, 2016, 12:08

I figured out the problem.
Apparently, my boundary conditions were incorrect. By changing to free-slip condition at the wall, the mass flow rates are exactly equal at the inlet and the outlet.

August 2, 2016, 13:33	Mismatch of mass flow rates after source term implementation in SU2	#1
akshaydeshpande New Member Akshay Deshpande Join Date: Sep 2014 Posts: 19 Rep Power: 12	Hi SU2 users, I have implemented a source term of dissipative heating in SU2 v. 4.2.0. The expression for the source term is $S = \frac{Q}{\pi^{3/2}.a.b.c} e^{(-((x-x_{o})/a)^{2} - ((y-y_{o})/b)^{2} - ((z-z_{o})/c)^{2})}$ The total power deposited is $Q = \iiint_{-\infty}^{\infty} Sdxdydz$ To test the implementation, I am running a simple source in a 2D rectangular box case. The calculations are in dimensional form. The B.C's I am using are : MARKER_SUPERSONIC_INLET at the inlet MARKER_SUPERSONIC_OUTLET at the outlet MARKER_FAR at the top and bottom edges The location of the source is at $(x_{o}, y_{o}) = (1.5, 0.5)$ , and I am getting the expected flow-field but the mass flow rates are not matching at the inlet and the outlet and therefore the energy balance is not working out. I have tried using both the Residual as well as Cauchy convergence criteria. For the later, I used CAUCHY_FUNC_FLOW as MASS_FLOW_RATE with maximum permissible CAUCHY_ELEMS corresponding to unsigned short datatype - but the result is still incorrect. I have also tried increasing the length of the domain. Please let me know if there is any other way to run the calculation for a longer time to achieve convergence or if my implementation of the source term is incorrect. I have attached the results below. Thanks in advance! Last edited by akshaydeshpande; August 2, 2016 at 21:56.

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August 12, 2016, 12:08		#2
akshaydeshpande New Member Akshay Deshpande Join Date: Sep 2014 Posts: 19 Rep Power: 12	I figured out the problem. Apparently, my boundary conditions were incorrect. By changing to free-slip condition at the wall, the mass flow rates are exactly equal at the inlet and the outlet.