Simulation of Flow past a Cylinder for various Reynold's Numbers in SolidWorks


Diameter = 0.04 m
Length = 0.1 m
Density of Air = 1.225 kg/m3
Dynamic Viscosity = 18.6e-6 Pa.sec at 20 Degree Celsius
Reynold No. = 20, 40, 100

We know that, Reynold No. = (Density x Velocity x Diameter)/Dynamic Viscosity

By applying above inputs in the Formula, we obtained:

Velocity for (Re = 20)  is  0.007592 m/sec
Velocity for (Re = 40)  is  0.015184 m/sec
Velocity for (Re = 100) is  0.037959 m/sec

Since, Flow through Time = Length/Velocity

Flow through Time for (Re = 20)  is  13.172 sec
Flow through Time for (Re = 40)  is  06.586 sec
Flow through Time for (Re = 100) is  02.634 sec

And, Simulation Time = 2 x Flow through Time

Simulation Time for (Re = 20)  is  26.344 sec  but computed for  27 sec
Simulation Time for (Re = 40)  is  13.172 sec  but computed for  14 sec
Simulation Time for (Re = 100) is  05.268 sec  but computed for  06 sec

Level of Mesh Refinement = 5



VELOCITY  Contours  Obtained  (Front  View):


(A)  Re = 20



Link  to  the  ANIMATION:                              click here



(B)  Re = 40



Link  to  the  ANIMATION:                              click here



(C)  Re = 100



Link  to  the  ANIMATION:                              click here



RELATIVE  PRESSURE  Contours  Obtained  (Top  View):


(A)  Re = 20



Link  to  the  ANIMATION:                              click here



(B)  Re = 40



Link  to  the  ANIMATION:                              click here



(C)  Re = 100



Link  to  the  ANIMATION:                              click here




From the above Velocity Contours,we found that the flow (Boundary Layer) separates in the downstream and the wake is formed by some eddies at the down side.Beyond the point of separation,the eddies are formed due to flow reversal.At Re = 20, eddies remain symmetrical but grow in size as Re increases. At Re = 40, the increasing wake oscillation starts shedding vortices into the stream. Upto Re= 100, the wake keeps increasing in a regular pattern. But If Re is increased beyond 100, eddies in the stream themselves will begin to oscillate and wake tends to become chaotic. At higher Re, the Boundary Layer will become turbulent. Then it will offer greater resistance to the flow separation compared  to the Laminar Boundary Layer.

In the Pressure Contours,we saw that the air is more compressed on the front surface and more spaced out on the back surface. It happens as the layers of air separate away from the surface and begin to swirl and leads to the Pressure Drag.



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The End