ME 303 FLUID MECHANICS EXPERIMENT #1
INVESTIGATION OF DRAG COEFFICIENT
IN CYLINDRICAL SURFACES
Information:
Let U denote the uniform speed of the motion and ρ the density of the fluid, then the
dynamic pressure in the undistributed stream, ½ ρ U2, is
½ ρ U2 = PO - po
where PO is total and po is static pressure.
Drag coefficient for a cylinder is defined as
CD 
D
½ U 2 dl
Where D is drag force, d is diameter and l is length of the cylinder.
In the experiment 2 cylinders will be used.
D (mm)
L (mm)
Cylinder 1
12.5
48
Cylinder 2
20
46
Procedure:
Drag force will be measured with counterweights. 4 different measurements for each cylinder
will be taken. Dynamic pressures will be noted for each step.
Report:
You need to graph the relation between drag force and dynamic pressure for each step.
Find drag coefficient.
Also graph the relation between Reynold’s number and drag coefficient. Discuss the
results.