Flow over a cylinder

AIM:-Simulate the flow over a cylinder using SOLIDWORKS for various factors of baseline Reynolds number,perform transient analysis.

GOVERNING EQUATIONS:-

Re=ρ⋅V⋅D/ν

where Re=Reynolds number

rho=denisty of air =1.127`kg/m^3`

V=inlet velocity

D=Diameter of the pipe

v=viscosity of air at 40`degc`

PRINCIPLE:-Usually fluid has three kinds of flows that is laminar,transistion,turbulent.For laminar flow the Reynolds number(Re)<2000,turbulent Re>4000,transistion 2000<re<4000.Transient flow means that the properties of fluid changes for a certain period of time and then become constant .When the air flows over a cylinder with velocity the air when it comes into contact with cylinder the air kinetic energy is suddenly drops to to zero and this energy converts to pressure energy because of which the flow takes place over the cylinder.Slowly the pressure energy coverts back to kinetic energy.If the body is not streamlined after this point the boundary layer gets seperated and a back pressure is created which drecreses the lift and increases the drag force.The point at which the kinetic enery becomes Zero there are called stagnation points.To increase the lift the body has to be streamlined.If thebody is not stramlined at higher velocity the boundary layer separation takes place and back presuure is created and vortexes occurs.

OBJECTIVES :-

1. To calculate the basline reynolds number.
2. To analyze the flow over cylinder for various 20%,40%,100% increase of basline reynolds number.
3. To create animations for pressure-velocity for all the three Reynolds number.

CODE:-

%Program to calculate basline Reynolds number
%velocity units m/s
V=10;
%density of air is 1.127 units:- kg/m^3
rho=1.127;
%Diameter of the pipe units:-m
D= 0.04;
%kinematic viscosity of water at 40deg units:-Ns/m^2
viscosity=16.92*10^-6;
%reynolds number 
R= V*D/viscosity

RESULT:-

REYNOLDS NUMBER AND INLET VELOCITIES:-

STIMULATION END TIME:-

BODY OF THE CONTENT:-

3-D MODEL OF CYLINDER:-

1. Select the part file.
2. Choose the front plane and draw a circle and extrude it to certain length.
3. Now save the part model so that it can be use for flow stimulation.

FLOW STIMULATION:-

1. Click on wizard.
2. After that choose the fluid,and make sure that we select the time dependent option.
3. We have to initially give velocity value in X-direction and click on finish.
4. Now choose Global mesh and choose the size of mesh .
5. Then click on run to solve .
6. After calculation select the results and choose the cutplots such that the cutplot is perpendicular to cylinder axis.
7. Now choose new parametric study so that flow stimulation for various factors of basline stimulation is made.
8. After the calculations save the cutplots, animations.

CUTPLOTS FOR THE 20% INCREASE OF REYNOLDS NUMBER:-

Velocity:-

Pressure:-

CUTPLOTS FOR THE 40% INCREASE OF REYNOLDS NUMBER:-

Velocity:-

Pressure:-

CUTPLOTS FOR THE 100% INCREASE OF REYNOLDS NUMBER:-

Velocity:-

Pressure:-

INFERENCES FROM THE CUTPLOTS :-

1. As the reynolds number is increased the velocity increases keeping constant all other factors.
2. Due to increase in velocity the flow is more and more turbulent,which increases flow instabilities.
3. Due to increase in Reynolds number pressure seems to be to raised by some time in each case.

CONCLUSION:-

1. Created 3-D model of cylinder.
2. Calculated the stimulated end time.
3. Created cutplots for velocities,pressure.
4. Created animations for velocities,pressure.