Overview
Domain Interfaces are used for:
-Connection of mismatched meshes (hex to tet for example)
The meshes may be in the same or different domains
“Domain” in Domain Interfaces is a little misleading
A single mesh file may contain non-matching mesh regions and require domain interfaces
-Changes in reference frames between domains
.Even if the mesh matches
-Connect different types of domains together (e.g. Fluid to Solid)
-Create periodic regions within a domain
Inserting Domain Interfaces
To create a domain interface right-click on the Flow Analysis or use the toolbar icon
Domain Interfaces and Boundary Objects
After creating a domain interface 3 new object are created in the outline tree
The interface object is at the Flow Analysis level
-This is the object you should edit to make changes to the domain interface
Within each domain a Side 1 or Side 2 boundary condition is automatically created
-In general do not edit these objects
-They will be automatically updated when changes are made to the interface object
Domain Interfaces Panel
Interface Models
The available Interface Models are:
Translational Periodicity
-Simulates geometries that have translational periodicity
-Allows for either the mass flow rate or the pressure change across the interface to be specified
-The quantity not specified will be part of the solution
Rotational Periodicity
-Simulates rotationally periodic geometries
General Connection
-For all other types of connections
-A Frame Change/Mixing Model and a Pitch Change apply to rotating domain cases. These are discussed in the Moving Zones lecture
Mesh Connection Method
1:1
-Only use this option if you are sure that the nodes on Side 1 and Side 2 of the interface match up exactly
-Not recommended for Fluid – Solid and Solid – Solid interfaces
GGI
-Use this option when the nodes on the two sides are not aligned
-For best results both sides should have fairly similar mesh length scales
-Fluxes are conserved across the interface
-If the size of the connection region for one side is different to the other, the connection will be automatically made between the mutually overlapping surfaces (for best results ensure both sides fully overlap)
-Possible to perform a connection where there is a “slight” gap or interference between the two sides of the GGI connection
The gap should be small relative to the mesh length scale
-When solving, GGI connections use more memory and CPU than 1:1 connections
Automatic
-This is generally the recommended option when available
In some cases only the GGI option will be available
-It will try to make a 1:1 connection if possible, otherwise GGI
-The Mesh Match Tolerance under Edit > Options > Mesh determines how close nodes need to be before a 1:1 connection can be made
The default value of 0.005 (0.5%) is a fraction of the local mesh length scale
-In some situations a GGI connection will be used even when nodes match 1:1
E.g. Fluid – Solid interfaces, since GGI connections are more accurate in these situations
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