Drag Force in Water

Hi hkatz1,

Welcome to CR4!

You have to give more specifics: cylinder material/surface roughness, water temp, cylinder diameter, sharpness of edge, water depth, velocity of travel (which will be used in the calculation; the type of calculation will depend if you are in laminar or turbulent flow), and maybe a few other parameters.

This is likely to help.

Mike

Hi Mike,

Thank you for your answer. I tried to avoid providing the full details but it seems unavoidable...

I am working on a laboratory mechanism. The cylinder is 60 mm long and 140 mm in diameter (no mistake in dimensions). It is made of sand cast SS304L with rough surface area and sharp edges. It moves upwards inside a large glass tube in a speed of 13 mm/sec until it gets to about 30 mm below water surface. Temperature of water inside the tube is around 24 degrees C.

I will be very glad if you can provide even a rough approximation of the drag force on the cylinder (I am aware that in order to pull the cylinder upwards you have to exert a much higher force than just the drag force).

hkatz1

For a rough approximation I would go for 0.5*ρ*V²*projected area (ie area perpendicular to direction of motion).

Cheers.........Codey