# Please Find out the Drag Coefficient for a simple vertical cylinder as per given data below. I was trying to get results as per IS 875 standard. Please go through it and let know the procedure for it.

Question asked by Naga Gopal on Jun 20, 2019

This is the procedure I followed to find out the Drag coefficient of cylinder, but the values are showing wrong. please run a test on it and share your knowledge with me.

Size: Dia 48.3x1000 mm.

Wind Velocity in X Direction = 47M/S

Input Data: General Settings

Analysis type – External

Fluids: AIR (Gases)

Flow type: Turbulent

Thermodynamic Parameters:

Parameters - Pressure, Density

Pressure- 1325 Pa

Density 1.2kg/m^3

Velocity Parameters:

Velocity in X Direction: 47 m/s

Velocity in Y Direction: 0 m/s

Velocity in Z Direction: 0 m/s

Computational Domain Size:

 X, -X Y, -Y Z, -Z Study1 0.6, -6m 1.0, -1.0 m 0.6, -0.6 m Study2 0.8, -0.8m 1.0, -1.0m 0.8, -0.8 m Study3 1.0, -1.0 1.0, -1.0m 1.0, -1.0 m Study4 1.2, -1.2 1.0, -1.0m 1.2, -1.2 m

Goals:

Applied Equation:

({GG Force (X) 1} *2)/ (1.2*47^2*3.14*0.5*.0483*1.0)

({SG Force (X) 1} *2)/ (1.2*47^2*3.14*0.5*.0483*1.0)

Standard Values:  Cft – 1.0 (Dvd <6) Cft is the required result as per standard.

(Standard Values Reference from IS 875 Part 3 Link mentioned below)

IS 875 Link (https://archive.org/details/gov.law.is.875.3.1987) Page no:40 Table no: 23

Achieved Values:

 Global Goal Surface goal Cf Value Average Cf Value Average Study1 0.88 0.87 0.88 0.87 Study2 0.88 0.87 0.88 0.87 Study3 0.89 0.88 0.89 0.88 Study4 0.89 0.88 0.89 0.88