#### Transport equation

## What is CFD transport equation?

A transport equation is any differential equation for any variable that we solve in CFD. The term “transport equation” conjures several different levels of expression in CFD.

## What is advection dispersion?

The term represents advective transport, represents dispersive transport, and is the change in concentration in the solid phase due to reactions ( q in the same units as C ).

## What is K in the heat equation?

It is widely used for simple engineering problems assuming there is equilibrium of the temperature fields and heat transport, with time. where u is the temperature, k is the thermal conductivity and q the heat-flux density of the source.

## Why is the wave equation linear?

The basic wave equation is a linear differential equation and so it will adhere to the superposition principle. This means that the net displacement caused by two or more waves is the sum of the displacements which would have been caused by each wave individually.

## What is scalar transport equation?

The transport equation describes how a scalar quantity is transported in a space. Usually, it is applied to the transport of a scalar field (e.g. chemical concentration, material properties or temperature) inside an incompressible flow.

## What is advection process?

In the field of physics, engineering, and earth sciences, advection is the transport of a substance or quantity by bulk motion. An example of advection is the transport of pollutants or silt in a river by bulk water flow downstream. Another commonly advected quantity is energy or enthalpy.

## What is the unit of diffusivity?

Diffusivity has an SI unit of m^{2}/s (length^{2} / time). In CGS units it is given in cm^{2}/s.

## What causes advection?

Very simply, advection occurs any time an airmass moves. When a warm airmass moves into an area previously occupied by a cooler airmass, Warm Air Advection (WAA) occurs. Thus when warm air begins moving into an area previously occupied by cooler air, less dense air is attempting to evict much denser air.

## Is heat an elliptic equation?

The steady state heat equation (also called the steady state heat conduction equation) is elliptic whether it is 2-D or 3-D. The unsteady heat conduction equation (in 1-D, 2-D or 3-D) is parabolic in time.