CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   SU2 (http://www.cfd-online.com/Forums/su2/)
-   -   Mass Flow Inlet BC (http://www.cfd-online.com/Forums/su2/118930-mass-flow-inlet-bc.html)

AarBee June 6, 2013 17:10

Mass Flow Inlet BC
 
I am new to SU2 and trying to figure out how to make it work for my problem. Navier-Stokes, laminar, compressible.

I would like to specify inlet and outlet boundary conditions on a volume defined by everywhere else by wall and symmetry boundary conditions.

The outlet bc is pressure which falls under the standard syntax:
MARKER_OUTLET = (Outlet, pressure)

However, for the inlet bc, I would like to specify a mass flow rate being injected in the +Z direction. I am unable to figure out how to do this - could anyone point me to an tutorial/documentation.

Based on the Users Guide-Configuration file documentation, it would seem like I need to use a combination of MARKER_INLET (to specify inlet surface and flow direction) and MARKER_FLOWLOAD or MARKER_LOAD to specify mass flow rate (kg/sec). However, MARKER_INLET requires specification of pressure (and temperature) and MARKER_FLOWLOAD/MARKER_LOAD do not accept specification of direction.

So my questions are:
1. Do I use MARKER_FLOWLOAD or MARKER_LOAD to specify the inlet? Or do I have it completely wrong and need to approach this differently?
2. How do I specify the direction of flow at the inlet?

Thanks for any help.

taxalian June 7, 2013 06:14

Quote:

Originally Posted by AarBee (Post 432527)
I am new to SU2 and trying to figure out how to make it work for my problem. Navier-Stokes, laminar, compressible.

I would like to specify inlet and outlet boundary conditions on a volume defined by everywhere else by wall and symmetry boundary conditions.

The outlet bc is pressure which falls under the standard syntax:
MARKER_OUTLET = (Outlet, pressure)

However, for the inlet bc, I would like to specify a mass flow rate being injected in the +Z direction. I am unable to figure out how to do this - could anyone point me to an tutorial/documentation.

Based on the Users Guide-Configuration file documentation, it would seem like I need to use a combination of MARKER_INLET (to specify inlet surface and flow direction) and MARKER_FLOWLOAD or MARKER_LOAD to specify mass flow rate (kg/sec). However, MARKER_INLET requires specification of pressure (and temperature) and MARKER_FLOWLOAD/MARKER_LOAD do not accept specification of direction.

So my questions are:
1. Do I use MARKER_FLOWLOAD or MARKER_LOAD to specify the inlet? Or do I have it completely wrong and need to approach this differently?
2. How do I specify the direction of flow at the inlet?

Thanks for any help.

Well i think this is the right way to use it:

%
% Inlet boundary type (TOTAL_CONDITIONS, MASS_FLOW)
INLET_TYPE= MASS_FLOW
%
% Inlet boundary marker(s) with the following formats (NONE = no marker)
% Total Conditions: (inlet marker, total temp, total pressure, flow_direction_x,
% flow_direction_y, flow_direction_z, ... ) where flow_direction is
% a unit vector.
% Mass Flow: (inlet marker, density, velocity magnitude, flow_direction_x,
% flow_direction_y, flow_direction_z, ... ) where flow_direction is
% a unit vector.
MARKER_INLET= ( boundary_marker, density, velo_mag, 1, 0, 0 )

AarBee June 7, 2013 11:52

Thanks taxalian.

Quick follow up question - by requiring density and velocity at the inlet, we are essentially defining a pressure (I am working with an ideal gas) at the inlet which (in conjuction with outlet pressure bc) seems like over-constraining of the problem.

Following your post, I did a 'grep -ilr "MASS_FLOW" TestCases' to find a tutorial that discussed had the MASS_FLOW version of the inlet boundary condition but came up with no matches. Neither did I find any details about it in the configuration-file section of the Users manual - is there some documentation I am missing?

I also have a question about the suitability of SU2 to the problem I am trying to solve, but will post a separate thread for that.

taxalian June 7, 2013 12:21

Quote:

Originally Posted by AarBee (Post 432676)
Thanks taxalian.

Quick follow up question - by requiring density and velocity at the inlet, we are essentially defining a pressure (I am working with an ideal gas) at the inlet which (in conjuction with outlet pressure bc) seems like over-constraining of the problem.

Following your post, I did a 'grep -ilr "MASS_FLOW" TestCases' to find a tutorial that discussed had the MASS_FLOW version of the inlet boundary condition but came up with no matches. Neither did I find any details about it in the configuration-file section of the Users manual - is there some documentation I am missing?

I also have a question about the suitability of SU2 to the problem I am trying to solve, but will post a separate thread for that.


Well their is slight description available about the bc here:
http://adl.stanford.edu/docs/display...iguration+file
Additionally, consult the "config_template.cfg" in your /trunk folder. It should give you enough information.

taxalian June 7, 2013 16:19

Quote:

Originally Posted by AarBee (Post 432676)
Thanks taxalian.

Quick follow up question - by requiring density and velocity at the inlet, we are essentially defining a pressure (I am working with an ideal gas) at the inlet which (in conjuction with outlet pressure bc) seems like over-constraining of the problem.

Following your post, I did a 'grep -ilr "MASS_FLOW" TestCases' to find a tutorial that discussed had the MASS_FLOW version of the inlet boundary condition but came up with no matches. Neither did I find any details about it in the configuration-file section of the Users manual - is there some documentation I am missing?

I also have a question about the suitability of SU2 to the problem I am trying to solve, but will post a separate thread for that.

One more thing, you can try a simple farfield b.c.

Alternatively, may be the use of:
INLET_TYPE= TOTAL_CONDITIONS
MARKER_INLET= ( boundary_marker, total temp, total pressure, 1, 0, 0 )


All times are GMT -4. The time now is 01:14.