Final Answer:
The mass flux
of the fluid through the cross-section of the cylindrical pipe is given by the formula
, where
is the cross-sectional area of the pipe. For a cylindrical pipe,
. Therefore,

Step-by-step explanation:
In fluid dynamics, the mass flux represents the rate at which mass flows through a unit area. The formula
expresses this relationship, where
is the fluid density,
is the velocity of the fluid, and
is the cross-sectional area through which the fluid is flowing.
For a cylindrical pipe, the cross-sectional area
is given by
, where
is the radius of the pipe. Substituting this into the mass flux formula, we get
Additionally, the pressure gradient
influences the mass flux, so we multiply the formula by
to incorporate this effect.
Therefore, the final formula for the mass flux
in a cylindrical pipe with constant density
, viscosity
, and pressure gradient
. This equation provides a quantitative measure of the mass flow rate through the pipe, taking into account the key factors influencing fluid dynamics in this scenario.