Accelerating 2d Aerofoil

Iain Cartwright

I am not awear of any resources on the net or in fact anywhere on this subject.

Basically using a UDF I am simulating an accelerating flow, so the inlet velocity being a function of time, fluent is confused to provide something of a smooth acceleration via the time step being small (I have found t = 1e-4 is sufficient), I am interested in the steady acceleration but fluent does not simulate the acceleration as I would expect, taking somewhere in the region of 0.5 seconds of flow time to reach the desired acceleration and 1.5 seconds for transients to decay due to the increasing acceleration. This is a significant amount of time using a desktop computer and showing a property I would rather ignore at this time.

I would be interested if there was away of fluent solving the required acceleration at the start to avoid the occurrence of transients.

The graphs should give an indication to my problem.

http://www.umsu.manchester.ac.uk/hik...celeration.jpg

http://www.umsu.manchester.ac.uk/hik...C/Other/CL.jpg

The fuzziness in the CL graph is due to the rate of acceleration constantly changing slightly but oscillating around the desired value.

Any help would be greatly appreciated thanks

Iain Cartwright