About SC/Tetra - solver
Solver
The solver part uses the mesh and boundary
conditions defined in the preprocessor to solve
for the flow field. The SC/Tetra solver the
cell-vertex FVM, which reduces memory usage
while achieving high-speeds.
Functions
Completely Discontinuous Mesh Interface
ALE
Compressible/Incompressible Flow
Periodic Boundary
Adaptive Mesh Refinement
User Function
Turbulent Flow Analysis
Steady/Transient-State Analysis
Non- Newtonian Fluid
Heat Radiation
Diffusion
Fan Model
Particle Tracking
Chemical Reaction
Mixing Gas Analysis
COMPLETELY
DISCONTINUOUS MESH INTERFACE
SC/Tetra can manage fully discontinuous-mesh
interfaces. This means meshes with different
topologies can be connected and handled as one
model. This function is particularly helpful for
work discretization and when working with moving
boundaries.
Next | Top
ALE
The ALE function (Arbitrary Lagrangian Eulerian
for moving and/or rotating boundaries) makes it possible to model a moving
object in the simulation space. This function can be applied to two vehicles
passing each other or rotating fans. When an object moves, the mesh also moves
and/or gets deformed with with the object. This helps maintain accuracy.
Previous |
Top | Next
COMPRESSIBLE/INCOMPRESSIBLE FLOW
Although many flows can be solved as
"incompressible" (assumes the density is constant), "compressible" flow analyses
are required when treating chemically reacting gases, transonic and supersonic
flows, and gases with large temperature differences. The governing equations for
compressible flow simulation are very complicated, and significant know-how is
required to successfully solve them.
Previous |
Top | Next
PERIODIC BOUNDARY
The number of elements that must be solved can
be reduced by using periodic boundary conditions
when a model has symmetry within its shape. In
SC/Tetra an arbitrary surface can be chosen as a
periodic boundary. (Note: periodic
boundary conditions may not be applicable to a
symmetric model if the flow is not symmetric.)
Previous |
Top | Next
ADAPTIVE MESH
REFINEMENT
Built on the automated adaptive mesh refinement
function, SC/Tetra autonomously adds mesh
elements in the regions within the flow field
where there are a large field-variable changes
(large gradients0. This ensures highly accurate
analyses without needing to possess extensive
know-how about methods for achieving high
effective mesh-element densities.
Previous |
Top | Next
USER FUNCTION
SC/Tetra possesses a wide variety of pre-set
analysis conditions for common boundary
conditions and physical properties. In addition,
the user can define special "user functions" to
implement more, problem-specific conditions for
a particular model.
Previous | Top
| Next
TURBULENT FLOW
ANALYSIS
In general, turbulence effects must be
considered when the Reynolds number exceeds
approximately one thousand. Most, although not
all, engineering problems are in the turbulent
region and SC/Tetra supports several different
turbulence models to cover a wide range of
applications. The type model can be easily
switched in a dialog of the preprocessor.
-
Standard k-e model
-
RNG k-e model
-
MP k-e model
-
Realizable k-e model
-
Abe/Kondoh/Nagano model
(Linear low-Reynolds number k-e model )
-
Goldberg/Peroomian/Chakravarthy
(Linear low-Reynolds number k-e model )
-
Batten/Goldberg/Chakravarthy
(Non-Linear low-Reynolds number k-e model )
An example of how the realizable k-e model
improves the solution of the flow field compared
to the standard k-e model is shown in the
accompanying figure. The realizable K-e model
prevents the turbulence energy from becoming
negative and is more suitable for predicting the
separation point.
Previous |
Top | Next
STEADY/TRANSIENT-STATE ANALYSIS
 Physical
states that vary with time may be analyzed as a
"transient" problem. The accompanying figure is
a famous example of a time dependent flow called
the "Karman vortex street". A pair of vortices
is shed one after the other at a constant
frequency from both downstream edges of the
triangular bluff body. In this type of analysis,
the solution must be solved at every time step.
SC/Tetra offers various options for controlling
a transient simulation. These include the
Courant numbers as well as several variations,
user functions that control a change in an
interval of time, and restart calculations.
Previous | Top
| Next
NON- NEWTONIAN
FLUID
Viscous fluids can be classified as Newtonian
and Non-Newtonian. In Newtonian fluids, the
velocity gradient is directly proportional to
shear stress. Most fluids, like water and air,
are Newtonian. On the other hand, when the shear
stress becomes a non-linear function of the
velocity gradient the fluid is classified as
Non-Newtonian. In SC/Tetra, a dilatant fluid or
a pseudo plastic fluid can be treated as
Non-Newtonian. In a dilatant fluid (e.g.
starched water), the fluid gets stiff (the
viscous coefficient increases) as the
shear-stress incrementally increases For the
pseudo plastic fluid, such as soap or blood, the
fluid becomes suddenly smooth.
Previous |
Top | Next
HEAT RADIATION
 
SC/Tetra can perform full heat transfer analyses
including conduction, convection, and radiation.
In the accompanying figures, the outer wall is
heated by a hot spot at the center. The
temperature of the wall just behind the
obstructions is lower than the other part of the
wall since the obstacles block the heat
radiation energy.
SC/Tetra simulates the reflection, absorption
and scattering of heat radiation energy when
radiation energy passes through a media.
Previous | Top
| Next
DIFFUSION
SC/Tetra can model, diffusion phenomena such as
steam and smoke in air. Diffusion is often used
for the analysis of chemical-pollutant
dispersion. The figure shows the concentration
of smoke around person smoking.
Previous |
Top | Next
FAN MODEL
SC/Tetra contains a virtual fan model where a
specific P-Q (pressure-flow) characteristic can
be set within an arbitrary volume in the model.
Using this function, any commercially available
fan with known specifications can be modeled as
a simple cube in a computational domain. This
capability can significantly reduce the mesh
size. Fan problems that might normally be
considered transient analyses can be solved much
quicker using the fan function.
Previous |
Top | Next
PARTICLE TRACKING
SC/Tetra can solve a flow field that tracks the
motion of particles within the fluid. When
particles with a finite size and mass are
injected into a fluid, the particles interact
with the flow and momentum is transferred
between the fluid and the particles. For the
example shown in the accompanying figure, light
particles at the bottom of the tank are pulled
up to the surface by buoyancy.
Previous |
Top | Next
CHEMICAL REACTION
Chemical reactions can be simulated and analyzed
within SC/Tetra. The figures show the simulation
of the methane combustion process: the reaction
is described as CH4+2O2
® CO2+2H2O + (heat)---
carbon dioxide and water are produced from
methane and oxygen. Just a small amount of
methane is premixed with air (oxygen 25% and
nitrogen 75%), and then the mixture is promptly
heated at the bottom of the chamber. The
reaction excites further chain reactions. This
analysis is solved as a compressible flow.
MIXING GAS
ANALYSIS
SC/Tetra can handle a multiple-gas mixing
analysis with laminar/turbulent mass-diffusion
and/or chemical reaction. The analysis on the
right shows mixing between hydrogen and oxygen
under microgravity.
Previous |
Top
|
