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Help > Solve > Simulation Tutorials > Flow Analysis of a Manifold

Flow Analysis of a Manifold


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

To follow along, download Manifold.step  to your computer or access it using the Onshape link here.

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, figure 1 shows the hollow manifold geometry and figure 2 shows the extracted fluid volume.

As shown in figure 2, it is recommended to have the flow at the outlets flowing into a plenum region in order to move the pressure boundary condition away from the region of interest.

Note: Manifold.step downloaded from the above link is the same geometry as shown in figure 2.

Figure1. Hollow geometry of the manifold (left). Fluid volume, extracted from the hollow geometry (right).

Import the CAD file

  1. In OnScale Solve, from the Projects tab of the dashboard, create a new project by clicking on the New Project button.
  2. In the Modeler, import the CAD file using the icon  and clicking on Browse Files. Select Meters as the length unit.
  3. Alternatively, if you’ve an active Onshape account, you can import the geometry directly.

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 on Fluid Physics
  3. In the physics toolbar, under the Fluid Physics icon , select -> Flow and assign it to Face 12 under part Part 1. Enter 10 m/s in the properties panel.
  4. In the toolbar, under the Fluid Physics icon , select -> Pressure and assign it to Face 1 under part Part 1.
  5. Select Fluid Environment settings under Fluid Physics and in the property panel, enter the following values
    • Duration: 0.1s
    • Characteristic Length: 0.1m
    • Contraction Area Ratio: 1

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 Velocity
  3. 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.