Spatially averaging the Navier Stokes equations on a multiply connected domain

In summary, the conversation discusses the problem of bubbly flow in a cylinder and using FEM to study the effects of walls on drag. The speaker wants to solve the averaged equations to determine the drag dependence on distance from the wall, but is struggling to find literature on this method for multiply connected domains. They are advised to look into the work of Dr. John Kim and consider collaborating with other researchers for further insights.
  • #1
cathalcummins
46
0
Hi all,

The problem at hand is a bubbly flow in a cylinder: I'm using an FEM to identify how the walls effect the drag on bubbles in a flow. To test my results I want to set up an infinite cylinder with randomly distributed spheres and then average the Navier-Stokes equations over the entire length and polar angle.

I don't want to average over the radial direction as I want to solve the resulting "averaged equations" for moving walls: i.e I want to use the equations to find how the drag depends on distance from the wall.

I've attached two pictures to give an idea of what I'm talking about -- the second picture should be integrated through the polar angle too.

I can find almost no literature where the Navier-Stokes equations (or PDEs in general) are averaged in space over multiply connected domain. Can someone point me to an author/book which uses this method?

Cheers,
 

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  • #2


As a fellow scientist, I find your research topic very interesting. Bubbly flows are known to have complex dynamics and understanding the effects of walls on drag is crucial in various industrial and natural processes.

I am not aware of any specific literature that uses the method of averaging the Navier-Stokes equations over a multiply connected domain, but I suggest looking into the work of Dr. John Kim from the University of Michigan. He has done extensive research on fluid dynamics and has published several papers on the topic of averaging PDEs in complex geometries. His work may provide some insights and references for your research.

Additionally, I recommend reaching out to other researchers in the field and discussing your approach with them. Collaboration and exchanging ideas can often lead to new and innovative solutions.

Best of luck with your research!
 

FAQ: Spatially averaging the Navier Stokes equations on a multiply connected domain

What is the Navier Stokes equation?

The Navier Stokes equations are a set of partial differential equations that describe the motion of fluid substances. They are used to calculate the velocity, pressure, and temperature of a fluid, and are commonly used in fields such as engineering, physics, and meteorology.

What does it mean to spatially average the Navier Stokes equations?

Spatially averaging the Navier Stokes equations involves taking the average values of the equations over a certain area or volume. This is useful when dealing with a multiply connected domain, which is a space that contains multiple connected regions or boundaries. By averaging the equations, we can simplify the calculations and obtain a more general solution for the entire domain.

Why is spatial averaging necessary for a multiply connected domain?

In a multiply connected domain, there are multiple regions or boundaries that can affect the flow of fluid. By spatially averaging the Navier Stokes equations, we can take into account the interactions between these regions and obtain a more accurate solution for the entire domain. This is especially important in complex systems where the flow is influenced by various factors.

How is spatial averaging performed on the Navier Stokes equations?

Spatial averaging is typically done by integrating the Navier Stokes equations over the entire domain and dividing by the volume or area of the domain. This results in a set of averaged equations that can be solved for the average values of velocity, pressure, and temperature. The exact method of spatial averaging may vary depending on the specific problem and domain being studied.

What are the limitations of spatial averaging the Navier Stokes equations?

While spatial averaging can be a useful tool for simplifying complex fluid dynamics problems, it does have its limitations. The accuracy of the solution obtained through spatial averaging may depend on the size and shape of the domain and the assumptions made during the averaging process. It may also not be suitable for highly turbulent or non-uniform flows. Therefore, it is important to carefully consider the limitations and assumptions when using spatial averaging in fluid dynamics studies.

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