Mapped Inlet - Boundary Conditions

Mapped Inlet is a boundary condition that calculates a spatially uniform value by averaging the field from a specified outlet patch. This averaged value is then applied to the boundary where this condition is assigned. It is commonly used to recycle flow variables, such as temperature, from a downstream outlet back to an upstream inlet in a closed-loop system or for periodic-like behavior without strict geometric periodicity.

Unlike direct mapping, which copies a profile point-by-point, this condition integrates the field variable over the source patch area to compute a single mean value.

This boundary condition is available for:

The value applied to the inlet patch is calculated as the area-weighted average of the field values at the source patch (usually an outlet).

The formula for the uniform inlet value is:

Graphically, the Mapped Inlet boundary condition can be explained as in Figure 1.

Flow quantities of interest (such as velocity, pressure, temperature, or turbulent properties) are extracted from a specific cross-section at a certain downstream location, averaged, and then remapped onto the inlet. This process ensures that the precursor domain becomes an integral part of the overall solution domain. Mean turbulence properties generated within the main computational domain (e.g., k, epsilon) are averaged and applied at the inlet. This allows the simulation to maintain consistent mean flow conditions and turbulence levels.

The Mapped Inlet boundary condition may be used in closed circuits.

The definition of boundary conditions in SimFlow is both simple and intuitive. To specify the Mapped Inlet boundary condition, the user must navigate to the Boundary Conditions panel, select the appropriate boundary, and choose the correct option from the drop-down menu.

Let’s assume that we want to map the flow conditions for temperature from the outlet to the inlet using the Mapped Inlet boundary condition. To do that, from the drop-down menu in the Thermal tab, the user has to select from which boundary the results are mapped - Figure 2.

Map From - specifies the outlet patch from which the field values are averaged and mapped to this patch.

In this section, we propose boundary conditions that are alternative to Mapped Inlet. While they may fulfill similar purposes, they might be better suited for a specific application and provide a better approximation of physical world conditions.