Free And Forced Vortex Flow
Free vortex flow
- No external torque or energy required. The fluid rotating under certain energy previously given to them.In a free vortex mechanics, overall energy flow remains constant. There is no energy interaction between an external source and a flow or any dissipation of mechanical energy in the flow.
- Fluid mass rotates due to conservation of angular momentum.
- Velocity inversely proportional to the radius.
For a free vortex flow
- The free vortex flow is irrotational, and therefore, also known as the irrotational vortex.
- In free vortex flow, Bernoulli’s equation can be applied.
Forced vortex flow
- To maintain a forced vortex flow, it required a continuous supply of energy or external torque.
- All fluid particles rotate at the constant angular velocity ω as a solid body. Therefore, a flow of forced vortex is called as a solid body rotation.
- Tangential velocity is directly proportional to the radius.
ω = Angular velocity.
r = Radius of fluid particle from the axis of rotation.
- The surface profile of vortex flow is parabolic.
- In forced vortex total energy per unit weight increases with an increase in radius.
- Forced vortex is not irrotational; rather it is a rotational flow with constant vorticity 2ω.
Read: Types of fluid flow