angular velocity calculation in stirred tank

[jjw89]

I am looking for an equation that I can use to calculate the angular velocity across the surface area of a steel coupon. The coupon will be hang in side a stirred tank with x distance from the impellar and y distance from the bottom of the tank. Please help!

 

[cheute79]

Good luck on this. Modeling and scale-up of mixing systems is very much an art, and what you are asking for may well be a multi-variable partial differential, and based on many assumptions. There are factors to consider that you have not mentioned, such as rheology of the fluid, presence of any suspended solids and their size, relative density, and shape, baffle locations, sizes and other characteristics, temperature and heat exchange, the geometry of the agitator, the size of the agitator, the rpm of the agitator, the geometric relationships between the agitator and the tank, etc., etc.

You will probably find it much more straightforward to measure the velocity (perhaps with a hot-wire device or a pitot tube), or to place a floating solid at the distance from the wall and count it's RPMs, and calculate the average velocity.