Glossary - Computational Fluid and Particle Dynamics in the Human Respiratory System - page 339

Hagen-Poiseuille Flow is laminar viscous and incompressible and the flow is

flow through a constant circular cross-section that is substantially

longer than its diameter

Homogeneous fluid Fluid having constant density

Homogenous The assumption whereby each phase shares a common flow

multiphase flow field as well as other relevant fields such as temperature and

turbulence

Hydrostatic pressure The forces from a fluid acting on the submerged surface of

an object

Hydrostatics The study of liquids at rest

Ideal gas Is a concept that allows a simplified state for analysis. It

is a theoretical gas composed of randomly moving non-
interacting particles

Incompressible flow Fluid flow is considered incompressible when its density

remains constant within the flow domain. This is important
when setting up a CFPD problem so that simpler models can
be used for a constant density

Inhomogenous A more complex representation of multiphase flows where

multiphase flow each phase has its own flow (includeing temperature and

turbulence) field

Invisicid flow Flow without viscous effects, also known as potential

flow. The viscous terms in the momentum equation are
neglected

Irrotational flow Flow where the streamlines ever loop back on itself, typically

found in invisicid flows

Kinetic energy Is the energy which the fluid possesses due to its motion, and

is also usually defined as the dynamic pressure, determined
by 1/2

u 2

ρ

Lagrangian Describes fluid motion by focussing on a fixed location in

description space through which the fluid flows as time passes (compare

with Lagrangian description )

Laminar An organized flow field where fluid particles flow in layers

and do not readily mix.

Lift coefficient A perpendicular force to the flow direction exerted on an

object by the fluid flowing around it, normalised by dynamic
pressure and frontal area

Mesh Regions of the computational domain where the mathemat-

ical equations are applied to

Mesh independence The method implemented to ensure that any further refine-

ments to increase the number of mesh cells does not affect
the results

Newtonian Describes a fluid or flow that exhibits a constant viscosity

and there is a linear stress versus strain rate curve

Nodes Points in the mesh where data is stored

Non-Newtonian Describes a fluid or flow where the viscosity is not constant

and there is a non-linear relationship between the shear and