Fluid meshing

For 3D flow modeling, you must consider geometry creation and mesh creation together. Practical limits on model size, processing power, and solution time impose limitations on the number of elements you can solve on. At the same time, a relatively coarse mesh implies limitations on the level of geometry detail.

When you create a flow model for CFD analysis, you must define the 3D flow model. The 3D flow model consists of elements to model 3D fluid flow and flow simulation objects, primarily 2D, which characterize and delimit the flow.

In 3D flow modeling, just as in 3D solid modeling, the 3D elements contain the data that the flow solver needs for the analysis. However, unlike the solid material that makes up a design part, the fluid material occupies the void between the bodies, not the bodies themselves.

The fluid flow domain is fully meshed with 3D elements and models the internal volume available for the fluid flow. You can model the geometry of the fluid inside an assembly or a part with a complex shape.

Generating the fluid mesh

The flow solver supports the following types of fluid meshing:

Body-fitted fluid meshing

The fluid domain 3D mesh boundaries conform to the fluid domain boundaries represented by the faces of solid bodies. Body-fitted fluid meshing is useful when you want to control the meshing precision in specific regions where mesh size and orientation is important, for example, when using boundary layer meshing to align mesh elements with flow direction to model turbulence. For body-fitted fluid meshing, you create a polygon body for the void representing the fluid domain.

Immersed boundary meshing

In the immersed boundary mesh, the fluid boundaries that are represented by the faces of solid bodies are immersed in the mesh of regular three-dimensional cells. Immersed boundary meshing lets you quickly mesh a void representing the fluid domain, without cleaning the model extensively, and creating a polygon body representing the void.

The flow solver supports both meshing methods and solves the same mass, momentum, energy, and other flow equations on the fluid domains.

Simulation objects for flow modeling

The simulation objects that govern the fluid model are:

• Flow Boundary Conditions to define flow direction and rate, and external openings.

• 2D Screens and 3D Flow Blockages that impede the flow.

• Symmetry Planes, Moving Frames of Reference and Periodic Boundary Conditions that characterize specific geometric configurations of the flow volume and fluid movement.

Flow Surfaces and Solid Flow Blockages belong to both the 3D flow and the thermal models.

Preparing for fluid meshing

• Make the most of existing geometry.

• Create model geometry that can be meshed according to the requirements of the solver.

• Mesh the geometry.

• Define material properties.

• Assign element attributes.

How do I

Create a primitive

Learn more

Thermal meshing

Immersed boundary meshing

Duct network meshing

Primitives for Simcenter 3D Space Systems Thermal

Flow Boundary Condition

Screen

Flow Blockage

Symmetry Plane

Moving Frame of Reference

Periodic Boundary Condition

Flow Surface

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

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

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

Fluid meshing, Simcenter 3D 2021.1 Series

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