Isosurface

Introduction

Isosurfaces represent three-dimensional contours where a selected variable (e.g., velocity magnitude, shear strain rate, concentration) maintains a constant value throughout the domain. Once generated, other scalar values can be projected onto the surface by adding an Isosurface Variable, which is a child object to the isosurface parent added via the Isosurface Toolbar (see below). Isosurfaces are particularly useful for identifying coherent flow structures and interpreting spatial gradients.

An isosurface in CFD is similar to a 3D version of a contour map. The code identifies all points in the computational domain where the value of the variable is equal to the isovalue. The software then connects these points to create a surface. Isosurfaces are generated for both volume and slice outputs.

Property Grid

Isosurface Field UDF

none | This UDF defines the field variables used to draw isosurface contours. One output must be defined within the UDF: a floating point variable named field. This output variable is calculated across the lattice. The isocontour surface will be drawn where the field value equals the counter value. This is a voxel-based local UDF, calculated on a voxel-by-voxel basis using the local fluid properties.

Download Sample File: Isosurface Field

Value

This is the value for the isosurface. If the simulation temperature ranged from 300K to 500K and the user was interested in where the temperature was 425K, the user would put “425” in this field.

Isosurface Data

The isosurface topology and any data written to the isosurface using an Isosurface Variable are saved as binary .vtp files for visualization and analysis within M-Star Post. These visualization files are printed at both the Plane/Probe Output Write Interval and the Volume Output Write Interval, allowing for concurrent animation of isosurfaces and fluid/particle dynamics on 2D and 3D renderings. The name of the .vtp output file is linked to the dynamic name of the isosurface.

For more information about the .vtp file structure, see the Visualization Toolkit.

Isosurface Toolbar

Context-Specific Toolbar Forms	Description
Add Isosurface Variable	The Add Isosurface Variable function adds a field variable that is computed at the isosurface vertices.

For a full description of each option, see Context-Specific Toolbar selections.