This was very helpful! I think my issues were incorrect Quantity syntax and the added complication of not defining my function before using Manipulate (I've attached a notebook file where I did this wrong). I've also attached the notebook file that gives me what I wanted based on your example. I defined some of the parameters outside of the Manipulate expression instead of putting them in as unvarying quantities as you did, but this seems to also work. Do you see any potential problem with this method or are they equivalent?

Attachments:

DarcyEqn Wick(Ma...nb

DarcyEqn Wick(Ma...nb

Thanks Tim. That is a much less problematic way of defining 'g'

Hi William,

Since I am not quite sure about your equation and where you want to put quantities, I threw together this example of calculating capillary rise in inches with a variety of input units using Units Discovery and Manipulate:

capillaryRise[gamma_, theta_, rho_, g_, r_] := 
 2 gamma Cos[theta] / (rho g r)
Manipulate[
 UnitConvert[
  capillaryRise[gamma Quantity[1, (("Dynes")/("Centimeters"))], 
   theta \[Degree], Quantity[1, ("Grams")/("Centimeters")^3], 
   Quantity[9.8, ("Meters")/("Seconds")^2], r Quantity[1, "Microns"]],
   "inch"], {gamma, 1, 80}, {theta, 0, 180}, {r, 1, 1000}]

Does this example help?