Page 88 - TransAT_Tutorial_Manual

TransAT Tutorial Manual 2.3. Flow in an obstructed pipe

Simulation Parameters Tab
This tab is used to define the numerical properties of the simulation.

Simulation Type and Control Parameters
The simulation will be run unsteady because of the vortex shedding downstream the disk.
• Click Simulation Parameters on the left-hand side of the TransATUI

• Set the following parameters to solve for the unsteady flow.
Simulation Type : Unsteady

Control Parameters
− Total Simulation Time : 150
− Max Number of Time Steps : 500
− I n i t i a l Time Step : 0.2
− Autorelaxation : 0.8

Equations
In this section the convergence threshold is defined as well as the convection scheme and the
solvers used by TransAT. These parameters can be set for each equation individually. Set the
following parameters.

• In the equation tree, click All Quantities

• Set the Convergence Tolerance as follows
Convergence Tolerance : 1.0 e−2

• Click Momentum in the equation tree

• Modify the following properties

BMR I t e r a t i o n s : 10
Relative Solver Tolerance : 0.01

• In the equation tree, click Pressure

• Modify the BMR Iterations and the Relative Solver Tolerance fields besides the
equation tree as follows
BMR I t e r a t i o n s : 20
Relative Solver Tolerance : 0.1

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