QuickPart Surfaces

To account for ambient conditions, you specify values for the Ambient Temperature, the Heat Transfer Coefficient, and the Thermal Resistance from the external side of the QuickPart Surface to the environment.

You obtain the value of the equivalent sand-grain roughness height that is appropriate for your model either from the literature or empirically. To determine from an experiment:

• None: Does not apply a pressure jump.
• Fan: Imposes a pressure jump that is obtained from a fan performance curve that you specify. A fan performance curve describes the pressure rise across the fan—that is the static pressure measured downstream of the fan minus the total pressure that is measured upstream of the fan—as a function of the volumetric flow rate. The following Fan Curve Type options are available:
  • Polynomial: Defines the fan curve as a linear function. The pressure rise across the boundary is calculated as

    $p\left(\dot{v}\right)=-\frac{p_{\max }}{{\dot{v}}_{\max }}\dot{v}+p_{\max }$

    where $p_{\max }$ and ${\dot{v}}_{\max }$ are the specified Maximum Pressure and Maximum Flow, respectively.
  • Table: Defines the fan curve as a table of pressure rise versus volumetric flow rate as indicated by the imported Fan Curve File (*.csv). After the import, select the appropriate Pressure Units and Volume Flow Units. The pressure rise is calculated by linear interpolation between the data points in the table. Outside the intervals, the nearest limit is used.

  The specified fan performance curve must correspond to the actual fan operating rotation rate and temperature. If your data correspond to some standard rotation rate and temperature, scale the fan performance curve as required using the following established fan laws:

  $$\Delta P_2=\Delta P_1\times {({\omega }_2/{\omega }_1)}^2\times (T_1/T_2)$$
  $${\psi }_2={\psi }_1({\omega }_2/{\omega }_1)$$

  where $\omega$ is the fan rotation rate (rpm), T is the fluid temperature (K), and $\psi$ is the volumetric flow rate.

• Loss Coefficient: Computes the pressure loss as $0.5K\rho {\left|v\right|}^2$ where $K$ is the specified Pressure Loss Coefficient value.

• None: Does not apply a pressure jump.
• Fan: as for Stagnation Inlet boundary.
• Loss Coefficient: as for Stagnation Inlet boundary.

Optionally, you can specify a Contact Resistance, that is the resistance to conduction through the interface. The relation between the heat flux across the contact interface, the contact resistance $R$, and the temperature difference $\mathrm{\Delta }T$ is given by ${\dot{q}}^{\prime \prime }=\frac{\mathrm{\Delta }T}{R}$. Furthermore, you can provide an energy source for the interface. The specified Heat Source value defines the total rate of heat transfer through the interface.