Wednesday 25 December 2013
Inviscid Flow
An inviscid flow is the flow of an ideal fluid that is asumed to have no viscosity. In fluid dynamics there are problems that are easily solved by assuming that the flow is inviscid. It is a flow in which the viscous effects can be neglected.
The flow of fluids with low values of viscosity agree closely with inviscid flow everywhere except close to the fluid boundary where the boundary layers plays a significant role. At high reynolds numbers, flow past slender bodies involve thin boundary layers. Viscous effects are important only inside the boundary layer and the flow outside it is nearly inviscid. If the boundary layer is not separated then the inviscid flow model can be used to predict the pressure distribution with reasonable accuracy.
The inviscid flow model in ansys fluent can be used for simulations where nature of flow in not important to the problem like all the simple heat flow problems. Although air flow on an aircrafts body in with very high reynolds numbers(nearly inviscid) but the assumption of completely ignoring viscosity result in poor results and create problems while analysing high lift devices or analysis at high AOA. For better results the laminar flow model should be used.
Laminar Flow
Laminar flow is a type of fluid flow in which the fluid travels on smooth or in regular paths, in contrast to turbulent flow, in which the fluid undergoes irregular fluctuations and mixing. In laminar flow, sometimes known as streamline floe, the velocity, pressure and other flow properties at each point in the fluid remain constant. Laminar flow over a horizontal surface may be thought of as consisting of thin layers, or laminae, all parallel to each other, The fluid in contact with the surface is stationary, but all the layers slide over each other.
For eg. Laminar flow in a straight pipe may be considered as the relative motion of a set of concentric cylinders of fluid, the outside one fixed at the pipe wall and the others moving at increasing speeds as the centre of the pipe is approached. Smoke rising in a straight path from a cigarette is undergoing laminar flow. After rising a small distance, the smoke usually changes to turbulent flow , as it eddies and swirls from its regular path
An inviscid flow is the flow of an ideal fluid that is asumed to have no viscosity. In fluid dynamics there are problems that are easily solved by assuming that the flow is inviscid. It is a flow in which the viscous effects can be neglected.
The flow of fluids with low values of viscosity agree closely with inviscid flow everywhere except close to the fluid boundary where the boundary layers plays a significant role. At high reynolds numbers, flow past slender bodies involve thin boundary layers. Viscous effects are important only inside the boundary layer and the flow outside it is nearly inviscid. If the boundary layer is not separated then the inviscid flow model can be used to predict the pressure distribution with reasonable accuracy.
The inviscid flow model in ansys fluent can be used for simulations where nature of flow in not important to the problem like all the simple heat flow problems. Although air flow on an aircrafts body in with very high reynolds numbers(nearly inviscid) but the assumption of completely ignoring viscosity result in poor results and create problems while analysing high lift devices or analysis at high AOA. For better results the laminar flow model should be used.
Laminar Flow
Laminar flow is a type of fluid flow in which the fluid travels on smooth or in regular paths, in contrast to turbulent flow, in which the fluid undergoes irregular fluctuations and mixing. In laminar flow, sometimes known as streamline floe, the velocity, pressure and other flow properties at each point in the fluid remain constant. Laminar flow over a horizontal surface may be thought of as consisting of thin layers, or laminae, all parallel to each other, The fluid in contact with the surface is stationary, but all the layers slide over each other.
For eg. Laminar flow in a straight pipe may be considered as the relative motion of a set of concentric cylinders of fluid, the outside one fixed at the pipe wall and the others moving at increasing speeds as the centre of the pipe is approached. Smoke rising in a straight path from a cigarette is undergoing laminar flow. After rising a small distance, the smoke usually changes to turbulent flow , as it eddies and swirls from its regular path
