BOUNDARY CONDITION USING STAR CCM+

Aim

To model a pipe with radius 10 mm and lengths 50 mm for the below diagram

Stage 1 Modelling : Pipe

We model the geometry using the 3D CAD modeler in STAR CCM+

1) Open the simulation, Expand Geometry, right click on the 3D CAD Modeler and select New

2) The modeling window will open, select the XY plane and select Create Sketch.

3) Draw a cicle whose radius is 5 mm & exit.

4) Choose the plane which is perpendicular to the circle and draw the line using the give dimensions and structure.

Front view of the 2D drawing

Perspective view of the 2D drawing.

5) Close the sketch window and select the both sketches and right click on it and select "sweep".

6) Sweep dialog box will appear and select the circle for the geometry whish should be sweeped and select the the line for the direction for which the sweep should happen.

Profile after sweep

7) Close the 3D cad modeller and save.

8) Expand geometry >3D CAD model > Right click on the 3D model created and select New Geometry Part.

9) To split the pipe expand Parts > Pipe > Surface > Pipe, & select Split by part curves & give the BC's.

Stage 2 Surface Repair

Checked for surface errors & nothing was found.

Stage 3 Surface Wrapper

Since there were no surface errors, a surface wrap wasn't needed.

Right click on the pipe and click on the Assign to regions, a dialog box will appear in that chanhe the boundary setting as Create a boundary each part surface, & click ok.

Applying BC

1) Expand Regions > Regions > Boundaries.

2) The boundaries are listed for inlet select Velocity Inlet, for outlet select Pressure outlet & for the next body select wall.

Stage 4 Surface remecher and Volume Mesher.

1) Select Operations > New > Mesh > Automated Mesh.

2) A dialog box will appear Select the following

• Surface remesher
• Automatic surface repair
• Polyhedral Mesher (Core mesher) (It is selected because we are simulating for internal flow)
• Prism layer Mesher

and click ok

3) Expand Default Controls, and select Base size and give the value as 2.5 mm(less than the radius of the pipe 5mm).

4) Right click on the Automated mesh and select Execute.

5) After the volume mesh is complete we need to generate the mesh scene to do that, go to title bar and click Create/Open scene & select Mesh scene.

6) To see the quality of the volume mesh a cut section of the modeled can be viewed, for that right click on derived parts > New parts > Section > Plane.

7) A new window will open and orient the plane in such a way it is perpendicular to Y axis, and click ok.

8) To view the cut section, go to Scenes and select the Mesh Scene 1, then go to Scenes/Plots window, and Expand Displayers > Mesh 1 > Parts > Pipe.

9) Right click on pipe and select Hide and the plane section can be viewed

To check the mesh quality go to the Mesh icon in the title bar and click diagnostic

Mesh Report for the model

Cut Section of the model to view the Volume Mesh.

For setting BC's for inlet & outlet,

1) Goto Continua > Physics 1 > Select Models.

2) A dialog box will apeear and select > Steady > Laminar > Segregated flow > Constant Density & click close.

3) Go to Regions & expand it and click Regions > Boundaries.

4) Select pipe inlet >Physics Values > Velocity Magnitude in that give the value as 20 m/s

5) Select pipe outlet and check whether the value is 0 pa.