Restrictions on the Simplified Bernoulli
Practical applications of the simplified Bernoulli Equation to
real piping systems is not possible due to
two restrictions. One serious restriction of the Bernoulli equation in its
present form is that no fluid friction is
allowed in solving piping problems. However, in reality, the total head possessed by the fluid
cannot be transferred completely from one
point to another because of friction. Taking these losses of head into
account would provide a much more accurate description of what takes place
physically. This is especially true because
one purpose of a pump in a fluid system is to overcome the losses in
pressure due to pipe friction.
The second restriction on Bernoullis equation is that no work
is allowed to be done on or by the fluid.
This restriction prevents two points in a fluid stream from being analyzed if a
pump exists between the two points. Since
most flow systems include pumps, this is a significant limitation. Fortunately,
the simplified Bernoulli equation can be modified in a manner that
satisfactorily deals with both head losses
and pump work.