Boundary conditions in fluid dynamics
Boundary conditions in fluid dynamics are the set of constraints to boundary value problems in computational fluid dynamics. These boundary conditions include inlet boundary conditions, outlet boundary conditions, wall boundary conditions, constant pressure boundary conditions, axisymmetric boundary conditions, symmetric boundary conditions, and periodic or cyclic boundary conditions.
Inlet boundary conditions
In
Outlet boundary condition
In outlet boundary conditions, the distribution of all flow
No-slip boundary condition
The most common boundary that comes upon in confined fluid flow problems is the wall of the conduit. The appropriate requirement is called the no-slip boundary condition, wherein the normal component of velocity is fixed at zero, and the tangential component is set equal to the velocity of the wall.[1] It may run counter to intuition, but the no-slip condition has been firmly established in both experiment and theory, though only after decades of controversy and debate.[2]
Constant pressure boundary conditions
This type of boundary condition is used where boundary values of pressure are known and the exact details of the flow distribution are unknown. This includes pressure inlet and outlet conditions mainly. Typical examples that utilize this boundary condition include buoyancy driven flows, internal flows with multiple outlets, free surface flows and external flows around objects.[1] An example is flow outlet into atmosphere where pressure is atmospheric.
Axisymmetric boundary conditions
In this boundary condition, the model is
Symmetric boundary condition
In this boundary condition, it is assumed that on the two sides of the boundary, same physical processes exist.[4] All the variables have same value and gradients at the same distance from the boundary. It acts as a mirror that reflects all the flow distribution to the other side.[5] The conditions at symmetric boundary are no flow across boundary and no scalar flux across boundary.
A good example is of a pipe flow with a
Periodic or cyclic boundary condition
A
See also
Notes
- ^ ISBN 0-582-21884-5.
- S2CID 124269972.
- ^ "cyclic symmetric BCs". Retrieved 2015-08-09.
- ^ "cyclic symmetric BCs". Retrieved 2013-10-10.
- ^ "Symmetric boundary condition".
- ^ "cyclic symmetric BCs". Retrieved 2013-10-10.
References
- Versteeg (1995). "Chapter 9". An Introduction to Computational Fluid Dynamics The Finite Volume Method, 2/e. Longman Scientific & Technical. pp. 192–206. ISBN 0-582-21884-5.