33.7.8 Mass-Flow Inlet Dialog Box

The Mass-Flow Inlet dialog box sets the boundary conditions for a mass-flow inlet zone. It is opened from the Boundary Conditions task page. See Section  7.3.5 for details about defining the items below.

Controls

Zone Name   sets the name of the zone.

Momentum   displays the momentum boundary conditions.

Reference Frame   specifies the reference frame for the mass flow. If the cell zone adjacent to the mass-flow inlet is moving, you can choose to specify relative or absolute velocities by selecting Relative to Adjacent Cell Zone or Absolute in the Reference Frame drop-down list.

Mass Flow Specification Method   specifies whether you are defining Mass Flow Rate, Mass Flux, or Mass Flux with Average Mass Flux.

Mass Flow Rate   sets the prescribed mass flow rate for the zone. This flow rate is converted internally to a prescribed uniform mass flux over the zone by dividing the flow rate by the flow direction area projection of the zone. This item will appear if you selected Mass Flow Rate in the Mass Flow Specification Method list.

Note that for axisymmetric problems, this mass flow rate is the flow rate through the entire ( $2\pi$-radian) domain, not through a 1-radian slice.

Mass Flux   sets the prescribed mass flux for the zone. This item will appear if you selected Mass Flux or Mass Flux with Average Mass Flux in the Mass Flow Specification Method list.

Note that for axisymmetric problems, this mass flux is the flux through a 1-radian slice of the domain.

Average Mass Flux   sets the average mass flux through the zone. See Section  7.3.5 for details. This item will appear if you selected Mass Flux with Average Mass Flux in the Mass Flow Specification Method list.

Note that for axisymmetric problems, this mass flux is the flux through a 1-radian slice of the domain.

Supersonic/Initialization Gauge Pressure   sets the static pressure that will be used to initialize the flow field if the mass flow inlet boundary condition is selected for initializing flow properties (see Section  26.9.1).

Direction Specification Method   specifies the method you will use to define the flow direction. If you choose Direction Vector, you will define the flow direction components, and if you choose Normal to Boundary no inputs are required. See Section  7.3.3 for information on specifying flow direction.

Coordinate System   specifies whether Cartesian, Cylindrical, Local Cylindrical, or Local Cylindrical Swirl vector components will be input. This item will appear only for 3D cases in which you have selected Direction Vector as the Direction Specification Method.

X,Y,Z-Component of Flow-Direction   set the velocity-direction vector of the inflow stream. This vector does not need to be normalized (e.g., you can specify the vector (1 1 1) rather than (0.577 0.577 0.577)). These items will appear if the selected Coordinate System is Cartesian or the model is 2D non-axisymmetric.

Radial-, Tangential-, Axial-Component of Flow Direction   set the velocity-direction vector of the inflow stream. These items will appear for 2D axisymmetric cases, or for 3D cases for which the selected Coordinate System is Cylindrical or Local Cylindrical.

Radial-, Axial-Component of Flow Direction and Tangential-Component of Velocity   appear for a 3D Local Cylindrical Swirl coordinate system. Specify the X, Y, and Z-Component of Axis Direction and the X, Y, and Z-Coordinate of Axis Origin.

Turbulence   contains the turbulence parameters.

Specification Method   specifies which method will be used to input the turbulence parameters. You can choose K and Epsilon ( $k$- $\epsilon$ models and RSM only), K and Omega ( $k$- $\omega$ models only), Intensity and Length Scale, Intensity and Viscosity Ratio, Intensity and Hydraulic Diameter, or Turbulent Viscosity Ratio (Spalart-Allmaras model only). See Section  7.3.2 for information about the inputs for each of these methods. (This item will appear only for turbulent flow calculations.)

Turbulence Kinetic Energy, Turbulence Dissipation Rate   set values for the turbulence kinetic energy $k$ and its dissipation rate $\epsilon$. These items will appear if you choose K and Epsilon as the Specification Method.

Turbulence Kinetic Energy, Specific Dissipation Rate   set values for the turbulence kinetic energy $k$ and its specific dissipation rate $\omega$. These items will appear if you choose K and Omega as the Specification Method.

Turbulence Intensity, Turbulence Length Scale   set values for turbulence intensity $I$ and turbulence length scale $\ell$. These items will appear if you choose Intensity and Length Scale as the Specification Method.

Turbulence Intensity, Turbulent Viscosity Ratio   set values for turbulence intensity $I$ and turbulent viscosity ratio $\mu_t/\mu$. These items will appear if you choose Intensity and Viscosity Ratio as the Specification Method.

Turbulence Intensity, Hydraulic Diameter   set values for turbulence intensity $I$ and hydraulic diameter $L$. These items will appear if you choose Intensity and Hydraulic Diameter as the Specification Method.

Turbulent Viscosity Ratio   sets the value of the turbulent viscosity ratio $\mu_t/\mu$. This item will appear if you choose Turbulent Viscosity Ratio as the Specification Method.

Reynolds-Stress Specification Method   specifies which method will be used to determine the Reynolds stress boundary conditions when the Reynolds stress turbulence model is used. You can choose either K or Turbulence Intensity or Reynolds-Stress Components. If you choose the former, ANSYS FLUENT will compute the Reynolds stresses for you. If you choose the latter, you will explicitly specify the Reynolds stresses yourself. See Section  12.14.3 for details. (This item will appear only for RSM turbulent flow calculations.)

UU,VV,WW,UV,VW,UW Reynolds Stresses   specify the Reynolds stress components when Reynolds-Stress Components is chosen as the Reynolds-Stress Specification Method.

Thermal   contains the thermal parameters.

Total Temperature   sets the total temperature of the inflow stream.

Radiation   contains the radiation parameters.

Participates in Solar Ray Tracing   specifies whether or not mass-flow inlet participate in solar ray tracing.

External Black Body Temperature Method, Internal Emissivity   set the radiation boundary conditions when you are using the P-1 model, the DTRM, the discrete ordinates model, or the S2S model for radiation heat transfer. See Section  13.3.6 for details.

Species   contains the species parameters.

Specify Species in Mole Fractions   allows you to specify the species in mole fractions rather than mass fractions.

Species Mass Fractions   contains inputs for the mass fractions of defined species. See Section  15.1.5 for details about these inputs. These items will appear only if you are modeling non-reacting multi-species flow or you are using the finite-rate reaction formulation.

Progress Variable   sets the value of the progress variable for premixed turbulent combustion. See Section  17.3.3 for details.

This item will appear only if the premixed or partially premixed combustion model is used.

Mean Mixture Fraction, Mixture Fraction Variance   set inlet values for the PDF mixture fraction and its variance. (These items will appear only if you are using the non-premixed or partially premixed combustion model.)

Secondary Mean Mixture Fraction, Secondary Mixture Fraction Variance   set inlet values for the secondary mixture fraction and its variance. (These items will appear only if you are using the non-premixed or partially premixed combustion model with two mixture fractions.)

DPM   contains the discrete phase parameters.

Discrete Phase BC Type   sets the way that the discrete phase behaves with respect to the boundary. This item appears when one or more injections have been defined.

reflect   rebounds the particle off the boundary with a change in its momentum as defined by the coefficient of restitution. (See Figure  23.4.1.)

trap   terminates the trajectory calculations and records the fate of the particle as "trapped''. In the case of evaporating droplets, their entire mass instantaneously passes into the vapor phase and enters the cell adjacent to the boundary. See Figure  23.4.2.

escape   reports the particle as having "escaped'' when it encounters the boundary. Trajectory calculations are terminated. See Figure  23.4.3.

wall-jet   indicates that the direction and velocity of the droplet particles are given by the resulting momentum flux, which is a function of the impingement angle. See Figure  15.6.1TH-dpm-disp-bound-walljet in the separate Theory Guide.

wall-film   consists of four regimes: stick, rebound, spread, and splash, which are based on the impact energy and wall temperature. Detailed information on the wall-film model can be found in this section in the separate Theory Guide. The Number Of Splashed Drops must be specified.

user-defined   specifies a user-defined function to define the discrete phase boundary condition type.

Discrete Phase BC Function   sets the user-defined function from the drop-down list.

UDS   contains the UDS parameters.

User-Defined Scalar Boundary Condition   appears only if user defines scalars are specified.

User Scalar-n   specifies the whether the scalar is a specified flux or a specified value.

User-Defined Scalar Boundary Value   appears only if user defines scalars are specified.

User Scalar-n   specifies the value of the scalar.