Working with General Settings

Conventions for Preparing Body Segment Boundaries

Each passenger should be composed of fourteen body segments, which must be defined as separate boundaries. These boundaries correspond to the fourteen drop-down lists in the General Settings tab. Provided below is a diagram illustrating how the body segment menus have been arranged to approximate a human body.

In cases where the passenger touches solid regions, such as the torso and legs touching a seat, there must be a separate boundary for each solid segment as well.

It is important to note that boundary labels need to include the names of their respective body segments, as shown in the following screenshot. The thermal comfort wizard recognizes only the boundaries that are named in accordance with this convention.

If there are multiple people in the simulation, the boundary names should reflect this, for example Passenger2 LeftUpperArm.

Entering Passenger Properties

Begin using the wizard by selecting a value in the Number of Passengers spin box. This value should match the total number of people represented in the Simcenter STAR-CCM+ simulation.

Based on the number you specify, the Person setting contains a numbered list representing passengers. Select a passenger by the number, and complete your settings for that passenger throughout the tab, as described in detail in the rest of this section. Once all the settings have been provided for that passenger, you can change the Person number and enter the next set of data. The thermal comfort wizard retains your entries for each passenger.

For each passenger, begin by assigning the passenger a generic name, such as Passenger1. By default the first passenger has the name Driver, which can be changed.

Specify height, clothing resistance, and metabolic rate.

• The passenger Height is used by the TIM program to calculate the body mass distributions for the vascular system and the body surface area values.
• The Clothing Resistance defines the thermal conductivity of the passenger’s clothing in m²K/W.

• The Metabolic Rate is the rate at which the person releases energy to the surroundings as heat, which depends on their level of activity.

  It is set by selecting one of the Driver or Passenger radio buttons, or by entering a Custom value. When the Passenger option is selected the metabolic rate is set to 58 W/m^2, which is equivalent to a person who is seated and relaxed. When the Driver option is chosen the metabolic rate is set to 75.4 W/m^2 (passenger value x1.3), indicating that the driver is more active. The Custom option allows you to specify an alternative value by entering a scaling factor relative to 58 W/m^2, and is usually in the range of 0.8 to 2 (where 0.8 is equivalent to reclining, and 2 corresponds to medium activity.)

  
  
  

Make sure that the correct fluid region is selected under Select Model Region. The options in this drop-down list, and in similar ones for boundaries, correspond to the regions and boundaries that you created for this simulation file.

Select the appropriate boundary for each body segment.

Repeat this for any solid regions and boundaries that are in contact with the passenger.

For a multiple occupant model, the Passenger Filter can be used as a search function to display the relevant boundaries for a particular passenger. For example, before opening the thermal comfort wizard, the driver boundaries can be renamed to contain the word driver. Driver can then be applied in the filter to display the required boundaries in the drop-down menu for each body segment.

You can specify an initial body segment temperature in the Initial Temp text box. This is the value passed to the TIM program the first time it is called. Thereafter, the body segment temperature updates each time TIM is run. This body segment temperature differs from the boundary temperature specification set in the simulation tree. The boundary temperature specification is used during the initial iterations before calling TIM, and is then overwritten by the body segment temperature. All temperatures in the wizard are specified in degrees Celsius.

The Reload Boundaries button causes the Thermal Comfort Wizard to re-read the boundary information in the simulation and update options available in the Boundary Selection menus. This is used when boundary names have been changed in the simulation, and resets all boundary menus to -none-.