Mass Flux

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The rate at which mass is crossing the exit area of the pipe can found by multiplying the mass flux times the area.  The mass flux is simply the density times the velocity. 

The mass flux is the rate at which mass crosses a surface. It has units of mass per unit time per unit area.


The mass of fluid contained in the differential volume, dQ, is obtained by multiplying dQ by the density of the fluid.

                                   

 

The mass flow rate of fluid entering or leaving the differential surface, dS, is obtained by dividing the differential mass, dm, by the increment in time, dt.

      

 

The mass flux, J, is defined as the mass flow rate per unit of surface area.  The mass flux through the surface, dS, can be found from the above equation to be 

   

 

Learning Objectives;

Define the mass flux, compute the mass flux, compute the mass flow rate crossing a surface.