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Flow Models

The flow models you are going to learn about are all used by engineers, and they are all based upon performing a mass balance on a fixed control volume. This means that the flow models are based on the idea that within a fixed volume we observe that
Rate of Accumulation = Rate going in - Rate going out +/- Reaction within the Volume
Or, to put the same thing into an equation:

tex2html_wrap_inline22

Where we have the following:
M Mass of substance being monitored
t Time
tex2html_wrap_inline24 Influent: the total volumetric flow rate going into the control volume (in units of volume per time)
tex2html_wrap_inline26 Total concentration in the influent of the substance being monitored (in units of mass per volume)
tex2html_wrap_inline28 Effluent: total volumetric flow rate going out of the control volume (in units of volume per time)
tex2html_wrap_inline30 Total concentration in the effluent of the substance being monitored (in units of mass per volume)
k Reaction constant: not always actually constant, but often a function of the concentration of the mass being monitored (units in this equation are 1/time)

In this way, the units in each of the products turn out to be in terms of mass per time.


next up previous Index
Next: Assumptions Up: Introduction Previous: Formulation of Differential Equations

John Hoggard <hoggard@math.vt.edu>
Last modified: Sun Aug 10 16:28:09 EDT 1997