G D Johnston objects to Bryan Leyland's characterisation of tidal current energy in terms of static head--but this is the basis of Bernoulli's equation
and is conventional (Letters, PE March).
The unsteady Bernoulli's equation
is used for time historical evaluation of the velocity potential and is given as:
INVESTIGATION OF THE EFFECTS OF AN EXIT PIPE ON THE CALCULATION OF DRAINAGE TIME OF WATER FROM A TANK USING BERNOULLI'S EQUATION
Based on the Bernoulli's equation
in cross sections 1-1 and 2-2 (Fig.
is the integral of the Euler's equation and applies to general initial and final velocities and pressure.
Each section's resistance was then modeled by applying Bernoulli's equation
or Forchheimer-extended Darcy's Law.
tells us that if we have a fluid flowing in a pipe, and a sudden enlargement exists in the pipe, there will be a corresponding drop in pressure.
Subsonic airflow satisfies conservation of mass as well as Bernoulli's equation
so the ratio of test area to nozzle area can be calculated given the pressure developed by the fan and the desired test velocity.
This principle defines the conservation of momentum, which leads to Bernoulli's equation
when viscous forces are neglected, steady flow and constant density are assumed.
Solutions were obtained using (1) a three-dimensional solution of the Navier-Stokes equation using computational fluid dynamics and (2) Bernoulli's equation
and a momentum balance in one dimension.