Hi I am thinking of the flow patten around a cylinder with diameter of 0.1-0.2 mm in air. What will you expect about such flow field? Is there any differences from normal size cylinder. Thanks.

(1). Flow over a cylinder means: velocity of the flow, property of the fluid, and the size of the cylinder must be given to define the problem. (2). In your case, only one parameter is given. (3). What are the missing parameters? (4). From there, you can at least define the Reynolds number, Re=Rho*U*L/mu. (5). The flow pattern will be a function of the Reynold number.

Thanks for replying. Let me specify my question: Say when Reynolds Number is is larger than 1 or 30, there will be wake region. But when the size is so small, can we still imagine there will be wake as those in normal size cylinder?

(1). It is a function of the Reynolds number of your problem, it is not a function of the diameter of the cylinder.

i'm doing my project on flow inside a 2-stroke petrol engine.i would like anyone to help me in developing a moving grid(piston).is there any online articles available for the same.

Check out www.erc.wisc.edu/index.html.