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*CFD
Computational fluid dynamic analysis.

This option is used to control the transport of momentum, energy, temperature, species, and other scalar variables in both transient and steady-state fluid flow problems.

Products: Abaqus/CFD  Abaqus/CAE  

Type: History data

Level: Step

Abaqus/CAE: Step module

Reference:

Required parameter:

INCOMPRESSIBLE NAVIER STOKES

Include this parameter to specify an incompressible flow analysis.

Optional parameters:

ENERGY EQUATION

Set ENERGY EQUATION=NO ENERGY (default) to specify an isothermal flow problem.

Set ENERGY EQUATION=TEMPERATURE to specify a thermal (heat) transport problem with temperature as the primary transport scalar variable.

INCREMENTATION

This parameter is valid only for a transient flow problem.

Set INCREMENTATION=FIXED CFL (default) to set a fixed Courant-Friedrichs-Lewy (CFL) number for time marching. Abaqus/CFD automatically determines the stable time step based on the specified value of the CFL number.

Set INCREMENTATION=FIXED STEP SIZE to set a fixed time step for time marching.

STEADY STATE

This parameter is valid only for a steady-state flow problem.

Data lines for INCREMENTATION=FIXED CFL: 

First line:

  1. Suggested initial time increment (default=0.01). If the estimated value of the CFL number is greater than the specified CFL or the maximum allowable time increment, the specified value will be overridden by a time increment determined automatically by Abaqus/CFD for numerical stability purposes.

  2. Time period of the step (default=1).

  3. Scale factor for increasing the stable time step (default=0.025).

  4. Suggested CFL number (default=0.45).

  5. Interval to check stable time step (default=1).

  6. Maximum allowable time increment (default value is specified as the time period of the step).

Second line:

  1. Specified tolerance for the pressure projection scheme used for the initial divergence-free projection and for pressure equation subcycling near a steady-state solution (default=1 × 10–10).

  2. The time weight for the viscous/diffusive terms in the momentum and scalar transport equations (). Enter 0.5 (default) for the second-order accurate Crank-Nicolson method, 0.6667 for the Galerkin method, or 1 for the first-order backward-Euler method.

  3. Blank space.

  4. The time weight for the advective terms in the momentum and scalar transport equations (). Enter 0.5 (default) for the second-order accurate Crank-Nicolson method, 0.6667 for the Galerkin method, or 1 for the first-order backward-Euler method.

  5. The time weight for the treatment of boundary conditions (). Enter 0.5 (default) for the second-order accurate Crank-Nicolson method, 0.6667 for the Galerkin method, or 1 for the first-order backward-Euler method.

Data lines for INCREMENTATION=FIXED STEP SIZE: 

First line:

  1. Time increment (default=0.01).

  2. Time period of the step (default=1).

Second line:

  1. Specified tolerance for the pressure projection scheme used for the initial divergence-free projection and for pressure equation subcycling near a steady-state solution (default=1 × 10–10).

  2. The time weight for the viscous/diffusive terms in the momentum and scalar transport equations (). Enter 0.5 (default) for the second-order accurate Crank-Nicolson method, 0.6667 for the Galerkin method, or 1 for the first-order backward-Euler method.

  3. Blank space.

  4. The time weight for the advective terms in the momentum and scalar transport equations (). Enter 0.5 (default) for the second-order accurate Crank-Nicolson method, 0.6667 for the Galerkin method, or 1 for the first-order backward-Euler method.

  5. The time weight for the treatment of boundary conditions (). Enter 0.5 (default) for the second-order accurate Crank-Nicolson method, 0.6667 for the Galerkin method, or 1 for the first-order backward-Euler method.

Data line for steady-state flow: 

First (and only) line:

  1. Number of nonlinear iterations (increments). The default is 10000.