Mathematicians Find Way to Fight Fire Whirls

Research and Innovations 30 November 2017
UTMN scientists have created a model that fully depicts the dynamics of real whirlwinds, reported RIA news agency. 

For a long time scientists have been looking for a way to minimize the consequences of natural disasters, and in particular, fire whirls. As scientists are still unable to artificially reproduce these phenomena, the only way to study them in a laboratory is through mathematical and numerical simulation. This method allows researchers to not only study the physical processes of air swirls, but also develop recommendations on their liquidation using minimum resources. Numerical simulation of a moving continuous mass is still conducted on the basis of models that don’t take into account its compressibility or density.  

Illustration by Alina Polyanina, RIA news agency 

That is why the method of studying fire whirls invented by UTMN scientists is of great interest. Fire whirls and tornados occur when several fires merge into one and hot air flows collide and start swirling. The new method is based on the mathematical modelling of complex air flows, taking into account air compressibility, density and thermal conductivity as well as the influence of gravity and Coriolis forces on a whirlwind.  

“In the last ten years, we have been conducting research of gas dynamics under the guidance of Sergey Bautin. We have conducted several pieces of numerical and experimental research, the results of which became the foundation to a new theory of tornado-like whirlwinds. Our theory differs from traditional ones as it explains the reasons for whirlwind occurrence and suggests ways of liquidating them. It can be said that we have come closer to unveiling one of nature’s mysteries related to a variety of astonishing and dreadful atmospheric phenomena,” said one of the research authors, professor at the UTMN Department of Algebra and Mathematical Logic, Daria Barannikova

However, creating an equation is not enough – scientists have to solve it. And UTMN mathematicians have already found two solutions despite the model’s difficulty. One of them is stationary air distribution within the Earth’s atmosphere that was used during numerical calculations as initial conditions. The approximate solutions found describe the occurrence of dynamic air flows in tornado-like whirlwinds. Such modelling allows the calculation of whirled air flows parameters (temperature, density, pressure, speed and energy) at all points of the area under study. It also gives information on the reasons for whirlwinds occurrence, their energy sources and the directions of their rotation and movement. 

According to the data received, the rotation direction of fire whirls and tornados is opposite to the direction of usual tornados. They rotate clockwise in the northern hemisphere and counterclockwise in the south, which is connected to Coriolis force affecting air flow in such natural phenomena.   

The scientists said that the reasons why thermal whirls act as they do are common laws of nature. Local heating and local temperature fluctuations cause pressure differentials. As a result, air starts moving. The flow acts in accordance with the laws of thermodynamics affected by gravity and Coriolis forces. In the numerical simulation, the thermal whirl occurs without forced external twisting and changes its shape and size while moving along a horizontal surface, in accordance with natural fire whirls. 

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