Isosurface

Introduction

An isosurface in CFD is similar to a 3D version of a contour map. It shows all points in a 3D space where a particular variable has the same value. For example, an isosurface could show all points in a room where the temperature is 72 degrees Fahrenheit or where the concentration is 90% of the mean concentration. 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 the volume and the slice outputs.

In some cases, you can use the volume output to get the same information as the isosurface feature. However, the volume output takes more time and space to create. The isosurface feature is helpful when you know what value or range of values you are interested in before you run the simulation.

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 iso-surface. 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.

If Add Variable is selected, the following section will launch:

isoVar

Data Type

Definition

Scalar

Definition

Vector

Definition

Isosurface Contour UDF

user-defined units | This UDF defines the contour values to be computed along an isosurface. One output must be defined within the UDF: a floating point variable named value. Whereas the Isosurface Field UDF and associated value define where to draw the isosurface, the Isosurface Contour UDF defines what field values to map along the counter surface. This is a voxel-based local UDF, calculated on a voxel-by-voxel basis using the local fluid properties.

Download Sample File: Isosurface Contour

Units

User-defined units for the Isosurface Contour UDF.