Variational Principles for Topological Barotropic and Non Barotropic Fluid Dynamics
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Professor Asher Yahalom
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Abstract:
Variational Principles for Topological Barotropic and Non Barotropic Fluid Dynamics
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Professor Asher Yahalom
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Abstract:
Barotropic fluid flows with the same circulation structure as steady flows generically have commoving physical surfaces on which the vortex lines lie. These become Bernoullian surfaces when the flow is steady. When these surfaces are nested (vortex line foliation) with the topology of cylinders, toroids or a combination of both, we show how a Clebsch representation of the flow velocity can be introduced. This is then used to reduce the number of functions to be varied in the variational principles for such flows. I introduce a three function variational formalism for stationary and non-stationary barotropic flows. Non Barotropic flows add additional complications but also an additional natural commoving surface the entropy. We will discuss the implications of this for variational analysis.
Brief Biography of the Speaker:
Asher Yahalom is a Full Professor in the Faculty of Engineering at Ariel University and the Academic director of the free electron laser user center which is located within the University Center campus. He was born in Israel on November 15, 1968, received the B.Sc., M.Sc. and Ph.D. degrees in mathematics and physics from the Hebrew University in Jerusalem, Israel in 1990, 1991 and 1996 respectively. From 1994 to 1998 Asher Yahalom worked with Direx Medical System on the development of a novel MRI machine as a head of the magneto-static team. Afterwards he consulted the company in various mathematical and algorithmic issues related to the development of the "gamma knife" - a radiation based head surgery system. In the years 1998-1999 Asher Yahalom joined the Israeli Free Electron Laser Group both as postdoctoral fellow and as a project manager, he is a member of the group ever since. In 1999 he joined the College of Judea & Samaria which became at 2007 Ariel University Center. During 2005-2006 on his first sabbatical he was a senior academic visitor at the institute of astronomy in Cambridge. During his second sabbatical in the years 2012-2013 he was a visiting fellow of the Isaac Newton Institute for Mathematical Sciences also in Cambridge UK. Since 2013 Asher Yahalom is a full professor and since 2014 he is the head of the department of electronic & electrical engineering. Asher Yahalom works in a wide range of scientific & technological subjects ranging from the foundations of quantum mechanics to molecular dynamic, fluid dynamics, magnetohydrodynamics, electromagnetism and communications.