Defining Human Comfort Parameters in Fluid Physics

You can describe a set of factors in the fluid physics that help determine the level of comfort for human models in the simulation. As part of the human comfort specification, you can choose between two methods for defining how the mean radiant temperature (MRT) is calculated.

  • The view factor method models each human as a group of predefined surfaces, then computes surface-to-surface view factors for each predefined surface.
  • The globe temperature method represents the surface of each human model as an idealized globe and uses an approximation to compute the MRT value at each element in the fluid domain. These values, coupled with the clothing insulation value and the metabolic rate for the representative human, enables the app to calculate the PMV field for each representative human. When you select this option, you do not have to create any other human models in the simulation.
The viewfactor-based approach generally provides greater accuracy in computation of the MRT on the human surfaces, but it is computationally more expensive.

This task shows you how to:

Specify Human Comfort Parameters Using the Viewfactor Model Method

  1. Specify the Relative humidity (%) of the fluid.
  2. From the MRT specification type options, select View factor.
  3. Describe the method for describing the cluster size from the Cluster size specification options as follows:

    Option Description
    Facenum Specify cluster size in terms of faces in each cluster, then specify the number of faces in the Faces per cluster field that appears.
    Lengthscale Specify cluster size by specifying a maximum cluster length, then specify the length in the Cluster length limit field that appears.

  4. Adjust the Number of rays per cluster. For example, if your overall surface has 100 cells, a cluster size of 4 should yield 25 clusters.
  5. Adjust the Cluster angle limit, a value (positive or negative) that enables you to keep the clusters from deviating too far from a planar orientation, which could affect the accuracy of the computed viewfactors.
  6. Click OK.

Specify Human Comfort Parameters Using the Globe Temperature Method

  1. Specify the Relative humidity (%) of the fluid.
  2. From the MRT specification type options, select Globetemp, then specify the temperature and emissivity of the globes and the globe diameter.
  3. Specify the following default values that apply to the representative human for the globe temperature option:

    Option Description
    Clothing insulation Measure of the thermal insulation provided by clothing on the surface where the human boundary condition is placed.
    Mets Measure of the metabolic rate, the level of heat generation per unit area on the surface whre the human boundary condition is placed.

  4. Click OK.