Flow Analysis of an FDA Nozzle

This simulation tutorial will guide you through:

• Choosing a fluid material and setting up boundary conditions
• Setting up fluid environment settings
• Meshing fluid Volume
• Simulate and post-process CFD results

Note

For internal flow problems, a CAD program is needed to extract fluid volume from its corresponding solid model. An example on how to do so using Onshape can be found here. In this tutorial, this step is skipped.

Import the CAD file

1. In OnScale Solve, from the Projects tab of the dashboard, create a new project.
2. In the Tool Bar, click (+) and then Library. Under OnScale Library, Select Nozzle.
3. Select Meters as the length unit.

Assign a Fluid material to the geometry

1. In the Model Tree, select the part Part 1.
2. Using the Material dropdown in the properties panel, search for Water and assign to the selected part. (Note: Fluid Analysis will only work with “Fluids” material)

Setup boundary conditions

1. Select the tab.
2. In the Physics Tree, toggle off Mechanical Analysis an toggle on Fluid Physics
3. In the physics toolbar, under the Fluid Physics icon , select -> Flow and assign it the face named “Inlet” under Part 1. Enter 0.5 m/s for Velocity Magnitude in the properties panel.
4. In the toolbar, under the Fluid Physics icon , select -> Pressure and assign it to the face named “outlet” under Part 1. Keep Pressure value at 0 Pa . Click Done. Note that this pressure is a reference ambient pressure.
5. Select Fluid Environment settings under Fluid Physics and in the tree, enter the following values

1. 1. Duration: 0.1s
      • The time needed to obtain a converging solution is usually > 2 × flow pass  where a flow pass is defined as the average distance a fluid parcel travels (~0.14 m), divided by the inlet velocity ( 0.5m/s)
      • However, due to the nozzle contraction convergence will be achieved faster.
   2. Characteristic Length: 0.01m
      • For non-contracting channels, the characteristic length can be approximated to be the inlet diameter of the channel. This parameter controls the size of the hexahedral mesh cells that will be created. For the default mesh:

1. 1. Contraction Area Ratio: 9
      • This is defined as the ratio between the inlet area and the smallest cross sectional area that the fluid propagates through.

Run a simulation

1. Select the simulator tab.
2. Click on the Launcher to run the simulation.
3. Once the meshing and estimation is complete, Select Launch to run the simulation study.

Analyze the results

1. Once the simulation has been completed, select Fluid Study 1 in the tree and click on Load Results to open the results in the Results tab.
2. In the tree, click Global Sensor.
3. In the properties panel on the right, select Vorticity from Output Datasets. Then, expand Slices, and move the slider, Slice X, from left to right to about the middle.
4. Use the cube at the bottom right corner to reset the view to “Right”
5. In the properties panel on the right, expand Time Duration and use the slider or press the play button to advance through the time frames.