vk.com/club152685050Modeling Two-Way Fluid|-Structurevk.com/id446425943Interaction (FSI) Within Fluent

23.3. Problem Description

The problem to be modeled in this tutorial is shown schematically in Figure 23.1: Problem Schemat- ic (p. 766).

Figure 23.1: Problem Schematic

Flow through a simple duct with vertical flaps is simulated as a 2D planar model. The duct is 10 cm long and 4 cm high, and the flaps are 1 cm tall and 0.3 cm thick. Turbulent air enters the duct at 30 m/s, flows around the flaps, and exits through a pressure outlet. Symmetry allows only half of the duct to be modeled.

23.4. Setup and Solution

The following sections describe the setup and solution steps for this tutorial:

23.4.1.Preparation

23.4.2.Solver and Analysis Type

23.4.3.Structural Model

23.4.4.Materials

23.4.5.Cell Zone Conditions

23.4.6.Boundary Conditions

23.4.7.Dynamic Mesh Zones

23.4.8.Solution Animations

23.4.9.Solution

23.4.10.Postprocessing

23.4.1. Preparation

To prepare for running this tutorial:

1.Download the fsi_2way.zip file here.

2.Unzip fsi_2way.zip to your working directory.

The files flap.msh and steady_fluid_flow.jou can be found in the folder. Note that the cell zone in the mesh file that will represent the solid zone is appropriate for an intrinsic FSI simulation,

which requires that only quadrilateral and/or triangular cell types are used and that a conformal mesh exists between the zones that will represent the solid and the fluid.

3.Use Fluent Launcher to start the 2D version of Fluent, with the Double Precision and Display Mesh After Reading options enabled. You must make sure that the Working Directory (in the General Options tab) is set to the one created when you unzipped fsi_2way.zip.

4.Read the journal file steady_fluid_flow.jou.

File → Read → Journal...

This journal file will read the mesh file flap.msh and set up and solve a steady fluid flow simulation that will serve as the starting point for the transient FSI simulation. Solving the steady flow problem first allows you to easily discern and resolve any convergence issues that are not related to the fluidstructure interaction.

As Fluent reads the journal file, it will report the text commands and solution progress in the console. You can also view the journal file in a text editor to see the settings used in this simulation. The final text command in the journal file will display contours of the velocity magnitude (Figure 23.2: Steady- State Velocity Magnitude (p. 767)).

Figure 23.2: Steady-State Velocity Magnitude

1.Mirror the display across the centerline (Figure 23.3: Duct with Mirroring (p. 768)).

View → Display → Views...

vk.com/club152685050Modeling Two-Way Fluid|-Structurevk.com/id446425943Interaction (FSI) Within Fluent

a.Select symmetry.2 in the Mirror Planes selection list.

b.Click Apply to refresh the display.

c.Close the Views dialog box and reposition the view as shown in Figure 23.3: Duct with Mirroring (p. 768).

Figure 23.3: Duct with Mirroring

•Save the initial case and data files as flap_fluid.cas.gz and flap_fluid.dat.gz.

File → Write → Case & Data...

Having completed an initial steady fluid flow simulation, the remaining steps are all concerned with setting up the structural calculations and obtaining the transient results for the deformation of the solid flaps.

23.4.2. Solver and Analysis Type

1.Specify the solver settings.

Physics → Solver

a.In the Solver group of the Physics tab, select Transient from the Time list.

b.Retain the default selection of Pressure-Based from the Type list.

23.4.3.Structural Model

1.Verify that a solid cell zone is already defined, as this is necessary to be able to enable a structural model. You can view the existing cell zones in the Outline View window.

2. Enable the linear elasticity structural model.

Setup → Models → Structure Edit...