FROM PAGE $51$ EXERCISE $2\mathrm{.}20,$ FROM THIS RESULT, OBTAIN THE EULER EQUATION FOR IDEAL FLUIDS IN CYLINDRICAL COORDINATES.

$2\mathrm{.}20.$ Derive the pressure gradient for cylindrical

coordinates in the same way as the pressure gradient

for Cartesian coordinates was developed. What

is the gradient operator in cylindrical coordinates?

Use the element shown in Figure P$2\mathrm{.}20.$ Hint:

Replace $sin(d\frac{O}{2})$ by $($dO$/2)$ and $cos(d\frac{O}{2})$ by $1.$

Figure P$2\mathrm{.}20$