thanks. the figure of 1.04 is the original gravity (not the viscosity as i previously said!). the stirrer will be a flat plate of total length 200mm, width 30mm.
Answer depends on impeller design and baffle configuration. Impeller/stirrer manufacturer should be able to supply these data.
Alternatively, see Perry's Chemical Engineering Handbook (pages 19-6 through 19-8 in the
5th edition). Or see unit operations book by McCabe, Smith, and Harriot. Other ChE books should have this too.
What you will see is a plot of the dimensionless "power number" versus impeller Reynolds number. Calculate Reynolds number, look up power number for your specific impeller design, and then find power. Torque is power/angular velocity in appropriate units. (If power is in ft-lbf/s, and angular velocity is in radians/s, then torque will be in ft-lbf.)
See also:
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Note that the conventional definition of Reynolds number for the stirrer is somewhat illogical.
IMHO that is the kind of thing where an old engineer looks for a like product and then does a quick test - only students have to actually figure such things
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