Suppose there is a fluid flowing in a tube with some flow rate. Let's say: $10cm^3s^{-1}$.
Now suppose I'm going to model this problem in 2D, by assuming that the tube is a rectangle. I was wondering whether there is a way to convert the volumetric flow rate into the 2D model. Ideally, some value with the units $cm^{2}s^{-1}$.
If the cross sectional area of the tube is: $A$ and the width of the rectangle is $W$, I do have a very rough estimate as $\left(\frac{10}{A}W\right) cm^{2}s^{-1}$, which is dimensionally correct. But I would like to know your opinion as well.