Modeling Human Comfort in a Fluid Flow Simulation

You can simulate the effects of representative human models in a flow simulation to examine their level of comfort. This workflow highlights all of the steps required to define human comfort in a flow simulation.

Simulating human comfort properly requires several additional steps in your simulation:

  1. Add one or more human models to your simulation in the Fluid Model Creation app.
  2. In the fluid physics, enable the human comfort model and then define the clustering parameters and the temperature specification method. For more information, see Defining the Fluid Physics of a Flow Simulation.
  3. Define a human boundary condition for each human model. The human boundary conditions enables you to define the boundaries of each human model's body and to configure its behavior. For more information, see Defining Human Boundary Conditions.
    Note: You can also define human groups to categorize humans with similar clothing and metabolic activity. Human groups can make it easier to define and organize data when you have a lot of human models in a simulation. For more information, see Defining Human Groups.
  4. Apply a gaseous material to the fluid domain around the human models. For more information, see About the Material Palette Interface.
  5. Create a steady-state step or a transient flow step. For more information, see About Steady-State Flow Steps or Transient Flow Steps.
  6. Specify the output requests for the simulation. There are three field output variables that are specific to human comfort simulations: the PMV (Predicted Mean Vote), PPD (Projected Percentage of Dissatisfied), and MRT (Mean Radiant Temperature). In addition, you can visualize the local surface temperature field on the human surfaces by requesting TEMP field output from the Energy output options.

    The locations where the solver computes human comfort values depend on your choice for how the MRT should be calculated. If you define MRT using the view factor method, which models each human as a group of predefined surfaces, the solver computes the values on each human surface. If you define MRT using the globe temperature option, which represents each human as an idealized globe, the solver app calculates these outputs for all fluid elements for the representative human specified. For more information, see Defining Output Requests.

When the simulation results are available, you can plot contours for the PMV, PPD, and MRT field output on each of the humans in the simulation. You can interpret these values in the following way:

  • PMV provides a measurement of the level of discomfort of each human in general and locally on parts of each human. Values range from -3 (cold) to +3 (hot). Ideally, each human model in the simulation should have a value close to 0 (neutral) over most of its surface.
  • PPD is similar to PMV, but it estimates the percentage of people satisfied with the level of thermal comfort.
  • MRT provides an approximation of the average temperature of all the surrounding surfaces to which each human is exposed. For example, a human close to a heating element such as a space heater would have a higher MRT value than the humans farther away. This difference can have an effect on the thermal sensation depending on whether the ambient air temperature is cold or warm.