Can an inviscid flow rotational? Potential Flow?

In summary, the conversation discusses the origin of vorticity and its relationship to viscosity in fluid flows. It is mentioned that even in an inviscid flow, the vorticity can still be constant and non-zero, leading to rotational flow. The difference between a viscous and inviscid shear flow is also addressed, with the conclusion that an inviscid flow can still have non-zero vorticity and angular momentum. The question of why a potential flow must be inviscid and if a viscous flow must be rotational is also brought up. Ultimately, the conversation ends with the request for clarification on these concepts.
  • #1
hanson
319
0
Hi all.
It seems to me that the origin of vorticity comes from viscosity, right?
So, if a flow is inviscid, can it be rotational?

For the example of a shear flow, U[y] = k*y, the vorticity a non-zero constant, k, everywhere, right? And we actually did not consider whether the flow is viscous or not when considering this shear flow. If the flow is inviscid, the vorticity is still constant and non-zero, right? So, it seems that an inviscid flow can still be rotational, right?

So, in the shear flow case, what is the difference between having the fluid being viscous and non-viscous? If the viscosity being zero but vorticity being non-zero, that means there is angular momentum (from non-zero vorticity) but no shear stress? Since the coefficient of viscosity is zero? It seems rather non-intuitive to me...We can have a zero shear stress but non-zero vorticity or angular momentum?

Also, why a potential flow must be inviscid? can it be just irrotational? Is that a viscous flow must be rotational?

Please kindly address my confusion. Thanks.
 
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  • #2
Good questions and all over my head, I'll be watching for an intelligent reply. You did get me thinking about Tesla turbines at 8:30 in the morning, now I'll get nothing done the rest of the day.:cool:
 
  • #3
Please help.
What is the difference between a viscous shear flow and an inviscid shear flow?
 

1. Can an inviscid flow be rotational?

Yes, an inviscid flow can be rotational. Inviscid flow refers to the flow of a fluid with no viscosity, which means there is no internal friction between the fluid particles. In such a flow, the fluid particles can rotate without any resistance, resulting in a rotational flow.

2. What is the difference between inviscid flow and potential flow?

Inviscid flow and potential flow are related concepts but they are not the same. Inviscid flow refers to the flow of a fluid with no viscosity, while potential flow refers to a type of inviscid flow where the velocity potential is constant throughout the flow field. In potential flow, the flow is irrotational, meaning there is no rotation of fluid particles.

3. Can viscous flow be potential flow?

No, viscous flow cannot be potential flow. Viscous flow refers to the flow of a fluid with viscosity, meaning there is internal friction between the fluid particles. In such a flow, the velocity potential is not constant throughout the flow field, and there is a presence of vorticity, resulting in a rotational flow.

4. What is the significance of potential flow in fluid dynamics?

Potential flow is a useful concept in fluid dynamics as it simplifies the equations of motion for inviscid flows. This makes it easier to analyze and understand the behavior of fluids in various scenarios, such as flow around objects or in different types of flow fields. Potential flow also serves as a building block for more complex flow models.

5. Can potential flow exist in real-life situations?

While potential flow is a simplified model for inviscid flows, it can provide a good approximation for certain real-life situations. In general, potential flow is a good representation of flow behavior for low-viscosity fluids, such as air or water. However, it may not accurately capture the full complexity of flow in high-viscosity fluids, such as honey or oil.

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