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Help > Simulation Tutorials > Flow Analysis of an FDA Nozzle

Flow Analysis of an FDA Nozzle

This simulation guide will guide you through:

  • Creating and importing a CAD geometry for the fluid flow analysis
  • Applying flow and pressure boundary conditions
  • Viewing simulation results

Preparing the CAD geometry:

For internal flow analysis, it is required that the fluid volume be extracted from the hollow geometry using a CAD program. In the below example, the left of figure 1 shows the hollow nozzle geometry and the right shows the extracted fluid volume.

Note: Nozzle.step used here is the same geometry as shown to the right of figure 1.

Figure 1: Hollow geometry of the nozzle (left). Fluid volume, extracted from the hollow geometry (right)

Below is video tutorial on how to setup the problem. Alternatively, you can read the following instructions.

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 to Face 6 under part 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 Face 5 under part 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
  • Duration: 0.1s
  • Characteristic Length: 0.01m
  •  Contraction Area Ratio: 9

Note: It is recommended to insert a where Net Distance is the distance traveled by fluid with the velocity entered in step 3. However, much smaller duration could be sufficient especially for geometries with strong area contractions. The characteristic length is used to determine the cell size such that The number of cells within a characteristic length depends on the mesh that will be chosen in the next step according to the table below. The Contraction Area Ratio is, simply, the ratio between the inlet area and the smallest cross-sectional area.

Mesh Size Number of Cells in a char L 
Very Coarse 15
Coarse 21
Medium 30
Fine 42
Very Fine 60

Run a simulation

  1. Select the Simulator tab.
  2. In the properties panel, select MESH & ESTIMATE. This automatically meshes your model, estimates how long the simulation will take to run, and estimates what the likely core-hour cost will be.
  3. Once the meshing and estimation process has finished, use the cost–time slider to select the level of computational resource that you want to use for this simulation.

    By using additional computational resources for the simulation (and hence spending additional core-hours), the simulation can be completed faster.

  4. Select RUN to run the simulation.

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, expand Dataset and the select Vorticity
  3. In the properties panel on the right, 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.

Follow this link for notes on advanced post-processing using Jupyter Notebook to extract flow rates.