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Introduction to BioMEMS

CFD-GEOM TUTORIAL 1

A Simple Rectangular Microchannel

1. Create points for the bottom of the channel

Select the Point create option/ Coordinate/Screen pick up option from the Geometry tab

Enter the X, Y and Z coordinates for the first point as (0,0,0) and click Apply Similarly, create the following points:

(0,50,0) ; (0,100,0) ; (100,0,0) ; (100,50,0) ; (100,100,0)

2. Connect the points using lines

Select the Line Creation/Polyline option from the Geometry tab

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Select the point at the origin in the Graphics window by pointing at it and clicking the left mouse button. The point changes color from green to red

Similarly choose another point and click the left mouse button. A line appears between the two points. Click Apply to create the line. Create lines between the other points as shown in the figure.

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3. Create Trimming Loop From the Geometry tab select the Surface Trimming options and then select Fit through curves. Click on a closed collection of lines, curves or edges and click Apply to form a surface.

4. Translating the section to make a 5 mm long channel Now press Ctrl+G to get the entities in the center of the screen. From the Geometry tab select the Translate option.

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Select all the entities by pressing Ctrl+A and click the middle mouse button to get the properties window.

Select X from the Translation Mode options. Enter the following values: Translation Distance = 100 (length of the section) Repeat (# Times) = 49 (50*100 µm = 5mm) Check the Duplicate option. Click Apply to get the 5mm long microchannel. Now press Ctrl+G to get the entities in the center of the screen.

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5. Create Quadrilateral Surface Mesh From the Mesh tab select the Unstructured Meshing options and then select Surface meshing.

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Select all the entities by pressing Ctrl+A and click the middle mouse button to get the properties window.

Mesh type options = Quad paving Maximum cell size = 5 Press the middle mouse button to Apply. To create triangular meshes, follow Steps 1-5 and then select Triangular Meshing instead of Quad Meshing in Step 6.

6. Extruding the channel in the z-direction From the Grid tab select the General Volume grid sweeping options and select the Linear Extrusion option. The Status Line Prompt you to select an entity to extrude Select all the entities by pressing Ctrl+A and click the middle mouse button to get the properties window.

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Select Z from the Direction options Enter the following values: Distance = 50 # Points =11 # Times = 1 Click Apply

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9. Set up Boundary Conditions Click on the BC/VC Editor tab. In the BC/VC Editor, click Model->Boundary conditions. The BC/VC Editor display lists all faces. To the right of the panel, the Type and Name fields are available.

Select the left Inlet face. (color change to red) • Change Type to Inlet • Change Name to Inlet_1 • Click OK

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Similarly choose the right inlet face: • Change Type to Inlet • Change Name to Inlet_2 • Click OK

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Note: after this step the color of the two inlets changes to yellow. Repeat the same procedure for the two outlet faces: Select both the outlet faces: • Change Type to Outlet • Change Name to Outlet • Click OK Note: after this step the color of the two outlets changes to orange.

10 Save GGD and DTF files. From the Menu bar select File->Save In the Save File window, select GGD from the File Filter options Enter Rectangular_channel.GGD in the File Name field and choose the directory you want to save the file in. Click the OK button From the Menu bar select File->Save as DTF option The Save File dialogue window opens. The DTF File Type option and the File Name with the DTF extension are already set. Select 3D from the DTF Options

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Change Geometry Units to Micrometers Check the Volume Check option Press the OK button 11 End of tutorial.