Need help understanding T-rex algorithm match type

f.aero77 · February 17, 2020, 23:04

Hi,

I'm very new to pointwise and am hoping to seek help to understand boundary condition types for the T-rex algorithm.

My question is, what does the match type exactly do and why is it being used?
Unfortunately, I don't really understand the definition in the website which is :

"Match: Sets bounding domains to have a grid point distribution that matches the growth of the interior anisotropic cells. Note that for the domains to be modified, you need to have the Push Attributes option checked on"

To give some context:
I am basically meshing around an aerobody, where my procedure states to consider the geometry and enclosures as wall type, but the inlet and the outlet boundaries are to have a match boundary condition type.

Can someone help me to understand why the inlet and the outlet are match type boundary conditions?

Thank you .

RcktMan77 · February 27, 2020, 12:35

Think of the simple case where you have a box with six sides, and you want to extrude layers of anisotropic cells from one face of this box (i.e., a flat plate). The adjacent domains to this plate (think the inflow and outflow boundaries) need to have their cell distributions modified from their original isotropic cell distributions to accommodate the anisotropic layers being extruded from the flat plate boundary. This is what the match boundary condition handles.

By default, the "Push" option is enabled meaning that match boundaries will have their cell/point distributions updated to match the extrusion growth parameters that result from the extrusion. If you disable this "Push" option, then you need to do this manually and ensure that the grid point distributions of connectors on match faces, which are aligned with the direction of extrusion, use a growth distribution function with the same initial spacing and growth rate that you're using in your T-Rex solver parameters.

February 17, 2020, 23:04	Need help understanding T-rex algorithm match type	#1
f.aero77 New Member Frances Iway Join Date: Feb 2020 Posts: 1 Rep Power: 0	Hi, I'm very new to pointwise and am hoping to seek help to understand boundary condition types for the T-rex algorithm. My question is, what does the match type exactly do and why is it being used? Unfortunately, I don't really understand the definition in the website which is : "Match: Sets bounding domains to have a grid point distribution that matches the growth of the interior anisotropic cells. Note that for the domains to be modified, you need to have the Push Attributes option checked on" To give some context: I am basically meshing around an aerobody, where my procedure states to consider the geometry and enclosures as wall type, but the inlet and the outlet boundaries are to have a match boundary condition type. Can someone help me to understand why the inlet and the outlet are match type boundary conditions? Thank you .

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February 27, 2020, 12:35		#2
RcktMan77 Senior Member Zach Davis Join Date: Jan 2010 Location: Los Angeles, CA Posts: 101 Rep Power: 16	Think of the simple case where you have a box with six sides, and you want to extrude layers of anisotropic cells from one face of this box (i.e., a flat plate). The adjacent domains to this plate (think the inflow and outflow boundaries) need to have their cell distributions modified from their original isotropic cell distributions to accommodate the anisotropic layers being extruded from the flat plate boundary. This is what the match boundary condition handles. By default, the "Push" option is enabled meaning that match boundaries will have their cell/point distributions updated to match the extrusion growth parameters that result from the extrusion. If you disable this "Push" option, then you need to do this manually and ensure that the grid point distributions of connectors on match faces, which are aligned with the direction of extrusion, use a growth distribution function with the same initial spacing and growth rate that you're using in your T-Rex solver parameters.