Answer:
If we assume that the fluid we are referring to is that of an ideal fluid (incompressible and non-viscous) and is undergoing a laminar flow, we can model this problem by Bernoulli's principle and equation.
Bernoulli's principle states that if the above conditions are met, the energy density of a fluid must be a constant, fixed value. This means that if the velocity of a fluid increases, other factors must decrease for the energy density of a fluid must be conserved. Bernoulli's Equation is the sum of the magnitude of the pressure, kinetic energy and potential energy of a fluid is equal to a constant. Therefore, if a velocity of a fluid increases, the kinetic energy of the fluid increases.
As a result, the pressure or the potential energy must decrease.
Both or only one may change; the result is dependent on the situation.