hi everyone,

im currently studying about drag coefficient for savonius turbine for my thesis.im trying to simulate the drag coefficient of half bucket design using flow simulation,but the result that i got from the simulation is not accurate compare to the text book drag.In my simulation result i got 0.8463  and the text book drag is 1.2.

I am very new to this flow simulation thing and just learned it bit by bit from the internet.I dont know where the problem is.here i attach some of the photo that maybe can help you guys find my mistake.

btw,i used water,0.4m/s external flow velocity,reynolds number is about 40000

please help me!