Transient flow over an cylinder
AIM
To make an external flow simulation at four different inlet velocities and then the reynolds number for different flow is to be calculated by increasing it to the 20%,40% and 100%.By using different reynolds number,the cylinder is simulated with recording the variations in the pressure with respect to the velocities for all the four simulations.
SPECIFICATIONS OF THE PIPE
Length of the pipe = 100mm;
Diameter of the pipe = 80mm;
CHARACTERISTICS OF THE PIPE
Fluid = Air;
Density = 1.225 kg/(m^3)
We know that reynolds number is given by,
Re = ǷVD/μ
where,
Ƿ = density of fluid;
V = velocity of fluid;
D = internal diameter of the pipe;
μ = dynamic viscosity of the fluid.
At first we take the initial velociry as 10m/s.So we get the reynolds number as 54143.64.Thereby incresing the reynolds number by 20%,40% and 100%,we get the corresponding velocities as given below,
%INCREASE(m/s) REYNOLDS NUMBER VELOCITY
INITIAL 54143.64 10
20% 64972.36 12
40% 75801.09 14
100% 108287.28 20
Domain length is = 2.5m
so, the velocity flow through time and the End time to be taken as 2 times the flow through time.
10 0.25s 0.50s
12 0.20s 0.40s
14 0.17s 0.34s
20 0.12s 0.24s
For initial velocity =10m/s:
velocity
pressure
YOUTUBE LINK FOR PRESSURE AND VELOCITY
WITH 20% INCREASE,VELOCITY AT 12M/S:
VELOCITY
PRESSURE
YOUTUBE LINK FOR VELOCITY AT 12M/S
WITH 40% INCREASE ,VELOCITY AT 14M/S:
VELOCITY
PRESSURE
YOUTUBE LINK FOR VELOCITY AT 14M/S:
WITH 100% INCREASE ,VELOCITY AT 20M/S:
VELOCITY
PRESSURE
YOUTUBE LINK FOR VELOCITY AT 100M/S:
OBESERVATIONS
Here it is observed that inlet velocity increses with increase in reynolds number in the flow over the cylinder.
The blue region denotes the increase in the velocity and red region denotes the change in the pressure also.