DRAFT
Advanced Techniques
Analytical Test Cases
Nondimensional Analysis of Governing Equation
This section reviews the numerical formulation used in SED2DWES and presents
an analysis of the use of the appropriate numerical coefficients for a given numerical
mesh and simulation design. The numerical mesh and hydrodynamic solution
present certain dimensional characteristics to the governing equations of sediment
transport. For a given mesh and hydrodynamic solution (RMA2) the transport
model will have certain numerical restrictions that will limit the ability of the
program to provide accurate solutions. A clear understanding of these limitations
can lead to either a redesign of the mesh and hydrodynamic simulation or guidance
in the compromises necessary in the numerical coefficients in SED2DWES.
Transforming The CD Equation
Recall that the convectiondiffusion equation (Equation 1), a.k.a. CD equation,
solved by SED2D is of the basic form:
∂C
∂C ∂
∂C ∂
∂C
∂C
 α1C  α 2 = 0
+u
+v


Dy
Dx
∂y ∂x
∂t
∂x
∂x ∂y
∂y
where
depthaveraged sediment concentration, kg/m3
C
=
T
=
time, sec
x,y
=
u,v
=
current velocity components in the x,y directions, m/sec
dispersion/diffusion coefficients for the x,y directions, m2/sec
Dx,Dy
=
α1
=
coefficient for the bed source/sink term, 1/sec
Advanced Techniques 43
Users Guide To SED2DWES