Documentation

Tutorial: 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 insights 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 re-circulation area near the junction and if the design has to be optimized accordingly.

In-compressible water flow through a pipe junction

Import tutorial case into workbench

The tutorial project “Tutorial 2: In-compressible water flow through a pipe junction” has been imported and is open in your SimScale Workbench.

Creating a Simulation

  • Once the Workbench is open, the CAD model CAD-pipe-junction_v1 will be loaded in the viewer.
  • Click Create Simulation to create a new simulation setup from this CAD model.
Start Simulation
Start Simulation
  • Select Incompressible as the Analysis Type and click ok.
Analysis Type
Analysis Type
  • A new tree will automatically be generated in the Simulation Tree panel, containing all parameters and settings required to start the simulation.
Simulation Tree
Simulation Tree
  • Set Turbulence model to Laminar (Leave other settings as they are).

    Turbulence Model

      Turbulence Model
  • Click Geometry in the tree and select the geometry CAD-pipe-junction_v1 from the list.
    Notice how the red circle next to Domain turns green when the selection is made.

Meshing

Geometry Assignment
Geometry Assignment
  • Next, click on the Mesh option
  • Select Hex-dominant (only CFD) as the Meshing Algorithm and click Ok.
  • Set Fineness to Coarse and keep the other parameter default (The goal of this tutorial is to get a first approximation of the flow field, so we start with a coarse mesh.).
Mesh Generation
Mesh Generation
  • Now click Generate at the bottom of the panel to start the mesh operation.
  • Find the meshing progress in the Job Status box in the lower left corner. The Meshing operation takes a little bit of time depending upon the complexity of the geometry and the fineness of the mesh. In this simple case, it will take around 4 to 5 minutes.
Mesh Status
Mesh Status
  • While the mesh is being generated, let’s go ahead and set up the simulation.

 Material Assignment

  • To create a new material, click on the ‘+’ button next to Materials in the simulation tree.
  • The Material Library will open. Scroll down to select Water and click Ok.
Material Library
Material Library
  • Now assign the material to the fluid volume by selecting the model in the viewer.
    Note: The color blue indicates that the assignment mode is on.
Material Assignment
Material Assignment

Boundary Conditions Assignment

Three boundary conditions(Inlet-1, Inlet-2 and Outlet) need to be assigned.

Boundary Conditions
Boundary Conditions

 

  • Add Inlet-1 first
    • To create a new boundary condition, click on the ‘+’ button next to Boundary conditions in the simulation tree. Select Velocity Inlet in the contextual menu.

      Add Boundary Condition

        Add Boundary Condition
    • Select the Inlet-1 face in the viewer.
    • This automatically assigns the face solid_0_face_0 to the velocity inlet.
    • Set the velocity in z-direction to -1.5 m/s.
Inlet-1
Inlet-1
  • Add Inlet-2
    • Add another boundary condition by clicking on the ‘+’ button next to Boundary conditions in the simulation tree. Create a second Velocity Inlet.
    • Select the Inlet-2 face in the viewer.
    • This assigns face solid_0_face_5 to the new velocity inlet.
    • Set the velocity in y-direction to -1 m/s.
Inlet-2
Inlet-2
  • Add Outlet
    • Add a third boundary condition by clicking on the ‘+’ button next to Boundary conditions in the simulation tree. Select Pressure outlet.
    • Select the Outlet face in the viewer to assign it to the pressure outlet boundary condition.
Outlet
Outlet
  • Check if Velocity inlet 1Velocity inlet 2 and Pressure outlet 3 are listed under Boundary conditions in the simulation tree.

Boundary Condition check

    Boundary Condition check

Simulation Run

Now you are ready to start your first simulation run.

  • Create a simulation run by clicking on the ‘+’ button next to Simulation runs in the simulation tree.
Create Run
Create Run
  • In the New Run dialog click Start to start the simulation run. (The simulation run takes around 2~6 minutes to finish)

    Start Run

      Start Run
  • Once the simulation run is finished, the Running status will change to Finished in the run settings panel. Additionally, details about the run can be seen in the Event Log.

Simulation Status

    Simulation Status

Simulation Results

  • Click Post-process results to load the solution fields in the post-processor.
  • Add a cutting plane to visualize the velocity inside the flow domain:
    • Click ‘+’ next to Cutting Planes.
    • Click on X in the Property panel to change the orientation of the cutting plane.
      Note: Turn the model in the viewer to see cutting plane properly.
    • Select Results in the Post-processor tree and scroll down to select Z Velocity to show the velocity field in clip direction.
      Note: Click on the little square to select ‘Cutting Plane 1’ as the filter to project the result field on.
Velocity Plot
Velocity Plot
  • The flow field clearly shows a recirculation area near the junction of the pipe where the z-velocity changes 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!

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