Flow over a cylinder using SOLIDWORKS
OBJECTIVE
- To run a baseline simulation and then calculate the Reynolds number.
- To increase the Reynolds number by a factor of 20%, 40%, and 100% then run the transient flow simulation.
THEORY
A common external flow configuration involves the circular cylinder or tube in crossflow, where the flow is normal to the axis of the cylinder.
For viscous fluids the flow pattern is much more complicated and the balance between inertia forces and viscous forces is important. The relative importance is expressed by the Reynolds number defined as
Where D is the tube diameter and ν the kinematic viscosity of the fluid.
As the fluid approaches the front side of the tube, the fluid pressure rises from the freestream value to the stagnation point value. The high pressure forces the fluid to move along the tube surface and boundary layers develop on both sides. The pressure force is counteracted by viscous forces and the fluid cannot follow the tube surface to the rear side but separates from both sides of the tube and form two shear layers. The innermost part of the shear layers are in contact with the tube surface and moves slower than the outermost part. As a result, the shear layers roll up. The flow pattern is dependent on the Reynolds number.
3D Model
Cylinder dimension
Diameter= 0.04m
Length of cylinder=0.05m
PROCEDURE
- Initially create the 3D Model of a cylinder with diameter of 0.04m and length of 0.05m.
- Go to the flow simulation click on wizard and give the file name and then we’ll give the other input parameters (velocity in x direction=10m/s, fluid=Air)
- Select the external flow and time dependent (total analysis time is 0.1 sec and output time is 0.01 sec) and then click finish.
- Computational domain length in x direction is 0.22+0.14=0.36m.
- Mesh automatically set as level 3.
- Run the simulation and we change the velocity to other calculations.
Calculation’s
Re = rho*Ut*D/mu
D = cylinder diameter
mu = dynamic viscosity
rho = density
rho=1.225;
U=[ 10 12 14 20];
D=0.04;
mu=1.81*10^(-5);
Re = (rho*U*D)/muReynolds number
27071.82320 32486.18785 37900.55249 54143.64641CALCULATING SIMULATION END TIME
velocity=distance of comptation domain/time
comptation domain=0.22+0.14=0.36m
- Flow Through Time(FTT)=0.36/10=0.036sec
End Time=2*FTT
=0.072 sec
2. Flow Through Time(FTT)=0.36/12=0.03sec
End Time=2*FTT
=0.06sec
3. Flow Through Time(FTT)=0.36/14=0.00.0257sec
End Time=2*FTT
=0.0514sec
4. Flow Through Time(FTT)=0.36/20=0.018sec
End Time=2*FTT
= 0.036sec
RESULTS
Velocity at 10 m/sec
Velocity at 12 m/sec
Velocity at 14 m/sec
Velocity at 20 m/sec
CONCLUSION
- We can see that the reynolds number increases then the velocity also increases and the flow through time decreases
- There is slightly variation in pressure so we can negligible.
REFFERENCES