Tutorial-02: Incompressible water flow through a pipe junction

Overview:

In this tutorial, a fluid flow simulation of water flow through a pipe junction is carried out. The objective is to get insight of the flow field at the junction of the pipe. There are two inlets and one outlet for this configuration. The simulation will show if there is a recirculation area near the junction and if the design has to be optimized accordingly.

Tut-2-FM-0

The tutorial project “Tutorial-02: Incompressible water flow through a pipe junction” has been imported and is open in your SimScale Workbench.
You will learn the following in about 5 minutes:

I. Mesh Generation

  1. Once the Workbench is open you will be in the Mesh creator tab and the CAD model CAD-pipe-junction_v1 loads in the viewer.
  2. Click New Mesh To create a mesh from this CAD model.
  3. Select Hex-dominant automatic (only CFD) as the Type of the mesh.
    MeshType
  4. In the Properties, set Fineness to 1 - Very Coarse. (The goal of this tutorial is to get a first approximation of the flow field, so we start with a coarse mesh.)
  5. Click Start at the header of the panel to start the mesh operation.
  6. Find the meshing progress in the Job Status box in the lower left corner.(The meshing takes around 1~3 min)
    JobStatus
  7. View the mesh in the viewer when the meshing operation is finished.
    MeshResult

II. Simulation Creation

  1. Click Simulation Designer on the top to start setting up the simulation.
    SimulationDesigner
  2. Click New in the Simulations, and click Create in the popup dialog.
  3. Select Fluid dynamics, and select Incompressible as the Analysis Type
    Analysis Type
  4. Set Turbulence model to Laminar (Leave other settings as they are).
    TurbulenceModel
  5. Click Save and a new tree will be automatically generated in Navigator with all the parameters and settings.
    NewTree
  6. Click Domain in the tree, select CAD-pipe-junction_v1 mesh in Available Meshes and click Save to assign the mesh to the simulation, which loads the mesh in the viewer
    PipeMesh

III. Material Assignment

  1. Click Materials in the tree, and click New to add a fluid material.
  2. Click Import from material library on the header of the panel to load material library, select Water click Save at the bottom of the panel to load the standard properties for water.
    MaterialLibrary
  3. Just left-click in the fluid volume in the viewer to assign it to the material. By the change of the mesh color to blue it can be seen that the matrial was successfully assigned to the fluid region and in the assignment box below the material settings it can also be seen the region0 was assigned to the material.
    Region0
  4. Click Save to finish material assignment

IV. Boundary conditions Assignment

Three boundary conditions(Inlet-1, Inlet-2 and Outlet) needs to be added.

BCs
  1. Add Inlet-1 first
    1. Right click the Boundary Conditions in the tree, select Add boundary condition in the contextual menu
      AddBC
    2. Rename the entry as Inlet-1 and select the Velocity inlet as Type
      Inlet-1Name
    3. Set the velocity as [0, 0, -1.5]
      Inlet-1Velocity
    4. Select the Inlet-1 face in the viewer.
      Inlet-1Face
    5. This automatically assigns the face solid_0_solid_0_face_0 to the velocity inlet.
      Inlet-1Assign
    6. Click Save to save Inlet-1
  2. Add Inlet-2
    1. Right click the Boundary Conditions in the tree, select Add boundary condition in the contextual menu
      AddBC-2
    2. Rename the entry as Inlet-2 and select the Velocity inlet as Type
    3. Set the velocity as [0, -1, 0]
      Inlet-2Velocity
    4. Select the Inlet-2 face in the viewer.
      Inlet-2Face
    5. Now you should see solid_0_solid_0_face_5 being assigned.
      Inlet-2Assign
    6. Click Save to save Inlet-2
  3. Add Outlet
    1. Right click the Boundary Conditions in the tree, select Add boundary condition in the contextual menu.
    2. Rename the entry as Outlet and select the Pressure outlet as Type
      OutletName
    3. Select the Outlet face in the viewer.
      OutletFace
    4. You can check if the correct face solid_0_solid_0_face_7 was assigned to the Outlet.
      OutletAssign
    5. Click Save to save Outlet
  4. Check if Inlet-1, Inlet-2 and Outlet are under Boundary conditions in the tree.
    BCFinish

V. Simulation Run

  1. Click Simulation Runs in the tree, and click New to create a Simulation Run. Ignore the warning dialog and click OK to proceed. The warning tells us that wall boundary conditions will be applied for all faces without a boundary condition specification. This is intended in our case for the pipe wall faces.
    Warning
  2. Click Start in the Create New Run dialog to start the simulation run.(The simulation run takes around 2~4 min)
    StartSimulation
  3. Once the simulation run is finished, Job Status at the lower left corner shows Finished.
    JobStatusSimulation

VI. Simulation Results

  1. Click Post-Processor on the top to switch to post-processing environment.
  2. Click Solution fields in the tree to load the results.
    SolutionFields
    Velocity
  3. Add a clipping plane to see the velocity inside the flow domain:
    1. Click Add Filter, and select +Clip to add a clipping plane to the result field.
      Clip
    2. Uncheck Show Plane in the Property panel, and click Apply to hide the clipping plane.
    3. Select u [point-data] in the Field to show the velocity field in the clip view and choose the Z-component instead of Magnitude.
    4. Click on Scale and select Rescale to Data Range
      Rescale
    5. Click to show the legend color bar.
      VelocityClip
  4. The flow field clearly shows a recirculation area near the junction of the pipe where the z-velocity changes the direction. The design decision should be to change the shape of the pipe as a next step and evaluate it again.

Congratulations! You just finished your first internal fluid flow simulation on SimScale!