Square velocity profile
 

hi,
i want to create square velocity inlet profile in cfx please help me.

You'll have to be a bit more specific than that. What have you tried so far?
Also, do you mean square in space (plug shape) or square in time (transient velocity profile)?

A plug shape is obtained by setting the velocity components on the inlet to a fixed value, while a square in time can be created by step functions.

thanks for reply.
i want square in time (transient velocity profile). the profile is attached here. please tell me about step function and how to obtain square velocity inlet profile.

A very simple expression could be:
(step((t-0.1[s])/1[s])+step((0.3[s]-t)/1[s]))*1[m/s]
which will give you a square between 0.1 and 0.3 s, with the magnitude 1 m/s. The argument inside the step function must be dimensionless.

instead of step function i have created following expressions to have continuous square velocity profile

LIBRARY:
CEL:
EXPRESSIONS:
Freq = 10 [rad s^-1]
InVel = if (TimeConst<=0, 0.05, vmax) [m s^-1]
TimeConst = sin(2*pi*Freq*t)
vmax = 30
END
END

The Plot of 'InVel' give required velocity profile.

i have used it for simple pipe flow and kept a monitoring point at inlet which shown correct profile velocity varying between 0-30m/s.
but when i was using same functions for my project it is not giving same profile it is varying between 0-1.2m/s why such thing is happening.
the geometry snap of my project is attached herewith. please help

Check all Boundary conditions, and try for some other cases. and apply same BC to your project.
Best Luck.