Cantilever Beam

Download mesh

Introduction

This example is a steady-state incompressible flow analysis example. This is a 1-way Fluid Structure Interaction(FSI) example to determine how a cantilever beam is deformed by air entering from the inlet region.

The cantilever beam is 5 mm thick, 50 mm long, and 150 mm high. We model only half of it and impose a symmetry boundary condition.

The geometry and mesh are shown in the figure below.

Simulation conditions are as follows.

  • solver : buoyantSimpleNFoam
  • turbulence model : $Standard$ $k-epsilon$
  • density : 1.225 $kg/m^3$
  • viscosity : 1.79e-5 $kg/ms$
  • flow condition : 80 $m/s$ at inlet

Start BaramFlow and load mesh

Run the program and select ‘New Case’ from the launcher. In the launcher, select Pressure-based for ‘Solver Type’ and None for ‘Multiphase Model’.

Use the given polyMesh folder. In the top tab, click [File]-[Load Mesh]-[OpenFOAM] in that order and select the polyMesh folder.

General

For this example, we’ll use default conditions.

Models

For this example, we’ll use Standard $k-epsilon$ model for turbulence.

Materials

For this example, we will use the properties of air.

Boundary Conditions

Each boundary condition is set as follows

  • Hex6_1_xMin : velocity Inlet
    • Velocity Specfication Method : Magnitude, Normal to Boundary
    • Profile Type : Constant
    • Velocity Magnitude : 80 (m/s)
    • Turbulent Intensity : 1 (%)
    • Turbulent Viscosity Ratio : 10

  • Hex6_1_zMax : velocity Inlet
    • Velocity Specfication Method : Component
    • Profile Type : Constant
    • X-Velocity : 80 (m/s)
    • Y-Velocity : 0 (m/s)
    • Z-Velocity : 0 (m/s)
    • Turbulent Intensity : 1 (%)
    • Turbulent Viscosity Ratio : 10

  • Hex6_1_xMax : Pressure Outlet
    • Pressure : 0 (Pa)

  • Hex6_1_yMin, Hex6_1_yMax : Symemtry
  • cantileverBeam_surface_0, Hex6_1_zMin : Wall
    • Velocity Condition : No Slip

Numerical Conditions

In this example, we’ll change the settings as shown below.

  • Pressure-Velocity Coupling Scheme : SIMPLEC
  • Discretization Scheme
    • Momentum : Second Order Upwind
    • Turbulence : First Order Upwind
  • Under-Relaxation Factors
    • Pressure : 0.9
    • Momentum : 0.9
    • Turbulence : 0.9
  • Convergence Criteria
    • Pressure : 0.001
    • Momentum : 0.001
    • Turbulence : 0.001

Monitor

In this example, we will monitor the force on the Cantilever. Go to [Monitors]-[Add]-[Forces] and select cantileverBeam_surface_0.

Then, set up the Surface Montior as shown below.

Initialization

Change the values as shown below

  • Velocity
    • X-Velocity : 80 (m/s)
    • Y-Velocity : 0 (m/s)
    • Z-Velocity : 0 (m/s)
  • Pressure
    • 0 (Pa)
  • Turbulence
    • Scale of Velocity : 80 (m/s)
    • Turbulent Intensity : 0.1 (%)
    • Turbulent Viscosity Ratio : 10

Enter the value and click the Initialize button at the bottom. Then click the [File]-[Save] menu to save the case file.

Run

Change the values as shown below, and click [Start Calculation] button.

  • Number of Iterations : 1,000
    • Save Interval : 100
    • Data Write Format : Binary
  • Selct [Parallel]-[Environment] in menu. Set Number of Cores as you want and select [Local Machine] for [Parallel Type].

When the calculation is started, you’ll see a graph of Residuals as shown below.

Post-processing

To start post-processing, click the ParaView button in [External tools].

We will plot the pressure field around a cantilever.

Change the Case Type to Decomposed Case.

Click the Slice button to cut a cross section.

Change the Axis Direction to Y Normal and the Origin to (200, 115, 125).

Then change the p at the top to p_rgh.

The pressure distribution around the cantilever is shown in the figure below.