Fluid #1: Flow Over a
Flat Plate
Introduction:
In this example you
will solve for the air flow velocity for flow over the flat plate, based
on the specified velocity, pressure boundary conditions, and the plate
dimensions.
Physical Problem:
Compute and plot
the velocity distribution of a flow of air over a flat plate.
Problem Description:
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The dimensions of
the plate are as shown in the figure. |
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Objective:
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To plot the
velocity profile around the plate. |
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You are required to
hand in print outs for the above. |
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Dimensions:
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The plate is 2
m long and is very thin. ANSYS does not allow infinitesimally
thin models so the plate is given a thickness of 0.001 m.
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The plate is
situated within a 4 m square. This arbitrary size serves to
set up the boundary conditions of air traveling over the plate.
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The velocity
of the air at infinite distance from the plate is 2 m/s.
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Atmospheric
pressure
is assumed on all faces except the face where velocity is input into
the system. |
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Material Properties
(Air):
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Density D=1.23
kg/m3 |
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Viscosity ρ =
1.79E-5 N-s/m2 |
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Figure:
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Create the larger
area, then the area defining the plate. |
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Subtract the
smaller area from the larger plate. |
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Define
the Element Properties as a 2D Air ElementDefine the Material
Properties of the Air Element (Density and Viscosity are the
important qualities) |
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Mesh the plate with
a mesh size of 0.01 on the edges of the inner plate, and 0.2
on the edges of the outer plate. |
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Apply Boundary
Conditions (No Slip along the edges of the inner plate, velocity along
the left line of the large plate, and Atmospheric Pressure (P=0 in
ANSYS) along the top, right and bottom lines of the large plate.
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Iterate 400 times
and solve. (Ideally the iteration count would be at least several
thousand times to make sure that the solution converges… but
computational time dictates that in order to be able to solve the
problem in a reasonable amount of time, the iteration number should be
trimmed down to 400) |
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Plotting the
Velocity distribution in the X direction, this is the answer you
should obtain with 400 iterations: |