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Aug 19, 2012

On 5:06 PM by Lalith Varun   7 comments

          FLUENT is a computational fluid dynamics (CFD) software which consists of modeling capabilities needed to simulate flow, turbulence, heat transfer and chemical reactions for a wide range of applications. It is an integral part in the design and optimization process of any product development.

          FLUENT has a wide range of boundary conditions that allows the flow to enter and exit the domain. This article helps you in selecting the appropriate boundary conditions for your specific application.

There are about 10 different types of flow inlet and exit boundary condition options in FLUENT.

1) VELOCITY INLET - It is used to define the velocity and other properties of the flow at the inlet. Intended for in-compressible flows

2) PRESSURE INLET - It is used to define the total pressure and other properties of the flow at the inlet. Flow direction must be defined else non-physical results can occur. Suitable for both compressible and in-compressible flows. Outflow can occur at pressure inlet conditions.

3) MASS FLOW INLET - It is used in compressible flows to define the mass flow rate at the inlet. It is not necessary in in-compressible flows as the velocity inlet itself fixes the mass flow rate.

4) PRESSURE OUTLET - It is used to define the static pressure at the outlet. It often gives better rate of convergence when back-flow occurs. Back-flow can occur at pressure outlet conditions and is assumed to be normal to the boundary. This must be used when problem is set up with pressure inlet.

5) PRESSURE FAR-FIELD -  It is used to model free stream compressible flow at infinity, with free stream mach number and static conditions specified. This is available only for compressible flows when density is calculated  from ideal gas law.

6) OUTFLOW - It is used to model flow exits where flow velocity and pressure are not known prior to solution of the flow. It cannot be used for compressible flows, with pressure inlet boundary condition and in unsteady flows with variable density. Can be used with velocity inlet.

7) INLET VENT - It is used to model inlet vents with specified loss coefficient, flow direction and inlet pressure and temperature.

8) INLET FAN - It is used to model an external intake fan with specified pressure jump, flow direction and intake pressure and temperature.

9) OUTLET VENT - It is used to model an outlet vent with specified loss coefficient and discharge static pressure and temperature.

10) EXHAUST FAN - It is used to model an external exhaust fan with a specified pressure jump and discharge static pressure.

          These boundary conditions help design and analyze the domain and model the flow through it.

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