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Fluid Analogy: Hydraulic Jump - White Hole

It seems that analogies between fluid flow and other physical processes continue to proliferate. Add to that list the analogy between a hydraulic jump (think smooth-shallow to rough-deep transition in a sink under a running tap) to a white hole (think black hole running backwards in time). Physicists at the University of Nice Sophia Antipolis, France recently showed through "...an experimental demonstration that the circular hydraulic jump represents a hydrodynamic white hole...".

Hydraulic Jump in a SinkHydraulic Jump in a SinkImage License: Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) by James Kilfiger

Fluid Dynamics News: F1, Bubbles, Nanoballs, and Flowers

Browsing through the news today I can across an interesting array of fluid dynamics related stories that I thought I'd share. So if you want to see how the Williams F1 team uses CFD and wind tunnels, or why a half-full (or is it half-empty?) bottle of water breaks when you hit it in a certain way (clue: cavitation), or how to make nanoballs (clue: bristles), and more, check out the links below.

Seiche Water Waves and Earthquakes

I think everyone is well aware of the link between tsunamis and earthquakes after the devastation wreaked in recent years on Japan and Indonesia. However, there is a lesser known water wave called a seiche that is limited to semi-enclosed and fully-enclosed bodies of water, such as lakes, bays, swimming pools, and even puddles. I went searching for links between earthquakes and fluid dynamics after I experienced a minor earthquake (4.0 magnitude) here in New England.

Fluid and Heat Cloaking Devices

While it seems that we are still a long way away from the cloaking devices seen in Star Trek, electromagnetic cloaking using metamaterials is now possible, at least in the laboratory. Not to be outdone, fluid flow and heat transfer have also recently joined the cloaking party.

For Submarines Stealth is EverythingFor Submarines Stealth is Everything

Morphing Tensile Structure

What if you could change the shape of a tensile structure according to the natural loads, such as wind forces, it experiences? In exploring this question researchers at the University of Stuttgart and the company Bosch Rexroth came up with a tensile canopy (membrane) - nothing new there. However, their novel design uses a feedback system driven by a sensor array connected to hydraulic rams that apply counter forces to natural loads.

Caedium Free Surface CFD Simulation for a Non-Newtonian FluidMorphing Tensile CanopyImage courtesy of Bosch Rexroth

Computers Cooled in Mineral Oil

A recent study by Intel using Green Revolution Cooling's CarnotJet System described immersing computer servers in mineral oil for electronics cooling. Of course the question that springs immediately to mind is why would you want to submerge sensitive electronics in a liquid?

Ketchup with your CFD?

If you are a ketchup manufacturer then maintaining your ketchup at the right consistency is a primary concern - same goes for ketchup connoisseurs. A new procedure developed by Bandulasena, et al at the University of Sheffield combines a simple experimental observation and Computational Fluid Dynamics (CFD) to characterize the viscosity of a non-Newtonian fluid, such as ketchup, so we can be confident that our ketchup will flow.

Caedium Free Surface CFD Simulation for a Non-Newtonian FluidCaedium Free Surface CFD Simulation for a Non-Newtonian Fluid

Why is CFD Difficult?

Of the 135 Symscape website visitors who voted in our latest poll, 37% cited mesh creation as the most difficult part of a Computational Fluid Dynamics (CFD) analysis. Configuring the geometry, deciding on physics and determining boundary conditions were clustered together as the next most difficult parts of CFD analysis. What is an engineer to do?

Poll Results: What is the most difficult part of CFD?Poll Results: What is the most difficult part of CFD?

Dam Break CFD Simulation

Can't get enough of Caedium's free surface simulations? Then this new post is for you. This animation shows a transient CFD simulation of a dam break over an obstacle. The simulation is performed in pseudo 2D, i.e., it is one cell thick.

Free Surface Tank Filling CFD Simulation

This animation, created by Caedium Professional, shows a transient multiphase CFD simulation of water filling a tank that is initially filled with air. The free surface is shown as blue for the air-side surface and red for the water-side surface. Each frame of the animation was automatically rendered by POV-Ray (a ray-tracer) through Caedium.


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