Encyclopaedia Index
[Section 2 of the PHOENICS Encyclopaedia article on multi-phase flow.

Click here for the start of the article]

Method (1): Two inter-penetrating continua: IPSA


This method uses the IPSA (Inter-Phase-Slip Algorithm), which entails solving the full Navier-Stokes equations for each phase.

In most circumstances, the two phases are taken as having the same pressure; but allowance can be made for the existence of a contact pressure between solid particles, when their volume fraction is close to unity.

This extra pressure is not shared by the fluid within which they move.

The IPSA method has been used in PHOENICS since 1981.

Click here for a lecture on IPSA.

Applications of IPSA

Applications of the use of this method include the simulation of:-

An example from the PHOENICS Input Library:


3D Nuclear-Power STEAM GENERATOR (Library Case: W802)

DETAILS:

Contours of volume fraction of steam, formed from water entering at the bottom of the cylindrical vessel

The steam-generation pattern is not symmetrical because the temperature of the water in the immersed U-tubes falls between inlet and outlet.

The water enthalpy, measured above a base value corresponding to the entry temperature, just below boiling point. The water becomes super-saturated where the heating rate is most intense.

Contours of upward velocity of steam. The flow pattern is far from being axi- symmetrical.

Contours of upward velocity of water. Note that the water velocities are smaller than the steam velocities, because of inter-phase slip.

The distribution of pressure.

The pressure diminishes with increase in height partly because of gravity and partly to accelerate the steam-water mixture.

Another example: a coal-fired furnace

Library case C111; the Q1 file

The IPSA method is used so as to simulate the different but interacting motions and exchanges of heat and mass between the coal and the burning gases.

Gas-phase temperature contours

Solid-phase temperature contours in the coal-fired furnace.

Note that the gas and coal temperatures are not the same.