Effect of Flow over a Cylinder MAE 5130 Viscous Flow Final Project By Shreya Raje

Introduction Formation of wake Vortex Shedding

Objective To find the effect of flow over a cylinder in terms of following parameters: Pressure Velocity Vorticity

Approach For this a two dimensional circular cylinder is drawn along with the direction of flow field perpendicular to its axis in gambit. Cylinder Flow Field Inlet Velocity Pressure Outlet Periodic Wall

Meshing

Parameters for Calculations for Laminar Flow An unsteady flow condition was selected to compute the parameters. Consider Flow Field to be Water Velocity (U) 0.5024 m/s Density (ρ) 998.2 kg/cubic m Kinematic Viscosity (µ) 0.001003 kg/m-s Cylinder Diameter (D) 0.25m Area of each Cylinder (A) 0.5 sq m Renolds number (Re) = (UxDxρ)/µ =2.5x105

Parameters for Calculations for Laminar Flow To see the effect of vortex shedding the frequency is calculated with Strouhal Number as 0.2 Strouhal Number, St= fxD/U f=0.20096 hz Cycle time,t=1/f=4.976sec time step size=4.976/25 =0.199sec

Contour of Static Pressure for Laminar Flow

Contour of Velocity Magnitude For Laminar Flow

Contours of Vorticity Magnitude For laminar Flow

Path lines with Vorticity Magnitude for Laminar Flow

Parameters for Calculations for Turbulent Flow An unsteady flow condition was selected to compute the parameters. Consider Flow Field to be Water Velocity (U) 2.5 m/s Density (ρ) 998.2 kg/cubic m Kinematic Viscosity (µ) 0.001003 kg/m-s Cylinder Diameter (D) 0.25m Area of each Cylinder (A) 0.5 sq m Renolds number (Re) = (UxDxρ)/µ = 1.244x106

Parameters for Calculations for Turbulent Flow To see the effect of vortex shedding the frequency is calculated with Strouhal Number as 0.2 Strouhal Number, St = fxD/U f = 1hz Cycle time,t=1/f=1sec Time Step Size=1/25=0.04sec

Contour of Static Pressure for Turbulent Flow

Contour of Velocity Magnitude For Turbulent Flow

Contours of Vorticity Magnitude For Turbulent Flow

Path lines with Vorticity Magnitude for Turbulent Flow

Results And Conclusion Sr No Parameter Flow Obtained Values Theoretical 1 Angle Laminar Approx 80o 82o Turbulent Approx 130o 120o 2 Coeffient of Drag 0.8166 1.2 0.4614 0.3