Contents
What is a flow transition?
Transitional flow is a mixture of laminar and turbulent flow, with turbulence in the center of the pipe, and laminar flow near the edges. Each of these flows behave in different manners in terms of their frictional energy loss while flowing and have different equations that predict their behavior.
What is Epsilon in OpenFOAM?
\epsilon. = Turbulent kinetic energy dissipation rate [ \text{m}^2 \text{s}^{-3}] The turbulent kinetic energy dissipation rate equation, \epsilon [Eq.
Which of the following solvers in OpenFOAM can be used for solving laminar flow of fluids select one?
A. 1 Standard solvers
| icoFoam | Transient solver for incompressible, laminar flow of Newtonian fluids |
| nonNewtonianIcoFoam | Transient solver for incompressible, laminar flow of non-Newtonian fluids |
| pimpleFoam | Transient solver for incompressible, turbulent flow of Newtonian fluids on a moving mesh |
What is nut file in OpenFOAM?
When you specify wall function for nut, you tell OpenFOAM to modify the momentum equation for the cells adjacent to the wall. The modification is that OpenFOAM calculates wall shear stress from log-law for these cells and put it in their equations.
Where is transitional flow used?
“Transitional flow” can refer to transition in either direction, that is laminar–turbulent transitional or turbulent–laminar transitional flow. The process applies to any fluid flow, and is most often used in the context of boundary layers.
What is transitional flow in Reynolds number?
Transitional or transient flow is the phase of flow that occurs between laminar and turbulent flow, and corresponds to Reynolds numbers that land between 2300 and 40005. In this type of flow, there is a mixture of laminar and turbulent flows present.
What is K Epsilon fluent?
K-epsilon (k-ε) turbulence model is the most common model used in computational fluid dynamics (CFD) to simulate mean flow characteristics for turbulent flow conditions. It is a two equation model that gives a general description of turbulence by means of two transport equations (partial differential equations, PDEs).
What is the difference between K Epsilon and K-Omega?
K epsilon is best suited for flow away from the wall, say free surface flow region, whereas k-omega model is best suited for near the wall flow region, where adverse pressure gradient is developed.
What is the value of Reynolds number for creeping flow?
In creeping flow the Reynolds number is very small (less than 1) such that the inertia effects can be ignored in comparison to the viscous resistance. Creeping flow at zero Reynolds number is called Stokes flow.
In which format is the data file in OpenFOAM saved?
OpenFOAM needs to read a range of data structures such as strings, scalars, vectors, tensors, lists and fields. The input/output (I/O) format of files is designed to be extremely flexible to enable the user to modify the I/O in OpenFOAM applications as easily as possible.
What is nut and nuTilda?
As I understand, nut is turbulent viscosity and nuTilda is kinematic turbulenr viscosity.
What is nut CFD?
For incompressible flow, OpenFOAM uses the kinematic version of viscosity. In this case you have kinematic viscosity ratio (nut/nu) = kinematic turbulent viscosity / kinematic molecular viscosity = kinematic turbulent viscosity / 1.5e-5. The kinematic turbulent viscosity (nut) is calculated by the turbulence model.