Simulation of a test setup with a glow plug

discovery_72 · July 28, 2015, 06:34

Hi!

I'm currently working on an experimental setup consisting on a rectangular pipe with a glow plug perpendicular to its longitudinal axis. I have modelled the glow plug as a cylinder penetrating the fluid with a given surface temperature.

I know the pressure at the inlet and since the velocity is really high, I have used pressure inlet as boundary condition at the inlet and pressure outlet at the exit. The mesh quality is good and it is accurate enough around the cylinder. I'm using a laminar model just to make sure that there is no problem with the mesh and/or the boundary conditions and I am not getting a converged solution.

Could anyone help me?

Steffen595 · July 28, 2015, 21:16

set the domain to the pressure you are at. Then inlet as mass flow and outlet 0 static average. If you then check in postprocssor, your fluid is at the domain pressure. Or if its gas, you see, the density is acc to the pressure.
It cannot converge, if you set a pressure at the inlet and the outlet, would be overconstrained.
http://www.arc.vt.edu/ansys_help/cfx_mod/i1300679.html

discovery_72 · July 30, 2015, 10:27

Quote:

Originally Posted by Steffen595

set the domain to the pressure you are at. Then inlet as mass flow and outlet 0 static average. If you then check in postprocssor, your fluid is at the domain pressure. Or if its gas, you see, the density is acc to the pressure.
It cannot converge, if you set a pressure at the inlet and the outlet, would be overconstrained.
http://www.arc.vt.edu/ansys_help/cfx_mod/i1300679.html

I used the pressure at the inlet and the outlet because I was afraid of having a shocked flow inside the pipe, which would mean that I am not free to select the mass flow rate. I am also trying to solve the problem as you said but it does not converge.

Steffen595 · July 31, 2015, 07:32

maybe try mass flow in and out, so at least it can adjust the pressure.
did you do mesh inflation?

July 28, 2015, 06:34	Simulation of a test setup with a glow plug	#1
discovery_72 New Member Daniel Join Date: Sep 2013 Posts: 5 Rep Power: 13	Hi! I'm currently working on an experimental setup consisting on a rectangular pipe with a glow plug perpendicular to its longitudinal axis. I have modelled the glow plug as a cylinder penetrating the fluid with a given surface temperature. I know the pressure at the inlet and since the velocity is really high, I have used pressure inlet as boundary condition at the inlet and pressure outlet at the exit. The mesh quality is good and it is accurate enough around the cylinder. I'm using a laminar model just to make sure that there is no problem with the mesh and/or the boundary conditions and I am not getting a converged solution. Could anyone help me?

July 28, 2015, 21:16		#2
Steffen595 Senior Member Join Date: May 2012 Location: Melbourne Posts: 161 Rep Power: 14	set the domain to the pressure you are at. Then inlet as mass flow and outlet 0 static average. If you then check in postprocssor, your fluid is at the domain pressure. Or if its gas, you see, the density is acc to the pressure. It cannot converge, if you set a pressure at the inlet and the outlet, would be overconstrained. http://www.arc.vt.edu/ansys_help/cfx_mod/i1300679.html discovery_72 likes this. Last edited by Steffen595; July 29, 2015 at 01:07.

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July 31, 2015, 07:32		#4
Steffen595 Senior Member Join Date: May 2012 Location: Melbourne Posts: 161 Rep Power: 14	maybe try mass flow in and out, so at least it can adjust the pressure. did you do mesh inflation?