Immersed boundary meshing

Use the 3D Immersed Boundary Mesh command to create an octree-based mesh, which represents the fluid domain for CFD modeling, using the immersed boundary method (IBM) available in the parallel flow solver.

To create an immersed boundary mesh, you select or specify:

• Bodies that form the boundary of the fluid domain.

• Bodies embedded in the main fluid domain that enclose separate individual fluid domains inside the main one.

• The size of cells on the boundary of the fluid domain and the size of the internal cells.

• An internal point from which the software starts the octree-based mesh generation.

• The destination mesh collector where you define the fluid material for your immersed boundary mesh.

Wrapping algorithm

The software uses the surface wrapping engine to create the immersed boundary mesh. The wrapping algorithm overlays an octree Cartesian rectangular mesh onto the geometry, and refines the octree-based mesh as it intersects the geometry until the target resolution is obtained. It generates a mesh of non-selectable and non-modifiable hexahedral cells. Nodes of the immersed boundary mesh cannot be moved or selected.

All geometric entities that represent boundaries enclosing the fluid domain are located within the generated immersed boundary mesh.

If the boundary of the fluid domain formed by the selected bodies has holes or cracks bigger than the minimum cell size, the wrapping algorithm cannot generate the mesh and displays the leaking path in the graphics window, which links the internal point to the outside region, going through the hole. To generate the mesh, you must close the hole or choose a bigger boundary cell size.

Leaking path

Meshing embedded polygon bodies

When you create the immersed boundary mesh, you can automatically mesh embedded polygon bodies (2), which represent a fluid domain that is connected to your original domain (1) through screens or internal fans. Regions (1) and (2) in the following image represent one enclosed fluid domain.

An immersed boundary mesh represents one fluid domain. To create completely separate fluid domains, even if one is embedded in the other, you need to create two separate immersed boundary meshes.

Mesh control

To control the resolution of the immersed boundary mesh for the CFD simulation using IBM, you can use the 3D Immersed Boundary Mesh command with the following mesh control density types:

• Size on Edge

• Size on Face

• Bounding Volume with no polygon body selected

IBM mesh with Size on Face mesh controls

When you create the bounding volume recipe for the Bounding Volume density type that is applied to the IBM mesh, you can only select the box, cylinder, or sphere bounding volume definition method.

Where do I find it?

Application	Pre/Post
Command Finder	3D Immersed Boundary Mesh
Simulation Navigator	Right-click the FEM node→New Mesh→3D→Immersed Boundary

How do I

Create a primitive

Learn more

Thermal meshing

Fluid meshing

Duct network meshing

Primitives for Simcenter 3D Space Systems Thermal

CFD simulation using the immersed boundary method

Look up more details

Meshing for Simcenter 3D Thermal/Flow, Electronic Systems Cooling, Space Systems Thermal

Special considerations for thermal meshing

Working with multi-layer shell elements

Geometry creation for body-fitted fluid meshing

Geometry preparation for immersed boundary method

Defining the mesh size for fluid modeling

Node to geometry matching in large dimension models

Meshing for turbulence modeling

Meshing consideration and wall functions

Thermal and flow element quality

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Simcenter 3D Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal boundary conditions

Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal

Immersed boundary meshing, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });