Wyngaard  suggested a tensor instead of a scalar representation of the eddy diffusivity to improve gray zone simulations using Eddy Viscosity closures.
where [K.sub.c] is the eddy diffusivity coefficient, z is the height, and t is time.
E., 1984: Vertical eddy diffusivity
in the ocean interior.
Kakamari, "Time dependent mathematical model of air pollution due to area source with variable wind velocity and eddy diffusivity
and chemical reaction," vol.
where C(x, y, z) denotes the concentration, [k.sub.x], [k.sub.y], [k.sub.z] are the cartesian components of eddy diffusivity and u, [upsilon], w are the cartesian components of wind speed, where x, y are cartesian horizontal distance and z is the height above ground surface.
However, these solutions are restricted to the specific case in which the source is located at the ground level and/or with restrictions to the wind speed and eddy diffusivity vertical profiles.
There are two approaches such as the eddy diffusivity
model and the surface renewal model which is widely used to model heat transfer at wall boundary (Tricoli, 1999).
[v.sub.E] is equal to eddy viscosity [v.sub.t].
Thus, the Reynolds stress (-[rho][bar.[u'.sub.i][u'.sub.j]]) and the Reynolds heat flux (-[bar.[u'.sub.j][theta]]) are modeled on the basis of the eddy viscosity and eddy diffusivity
5(b), which show calculated eddy diffusivity
using the QETE model with both types of the surface boundary conditions.
An analytical model using eddy diffusivity
is applied for predicting droplet concentration distribution and liquid film formation in a Venturi scrubber.