P M V Subbarao

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PEDAGOGY OF ADVANCED FLUID MECHANICS

• P M V Subbarao
• Professor
• Mechanical Engineering Department
• I I T Delhi

Faster Ways to Develop Balancing Skills for Omni
Present Non Countable Systems
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The Importance

• The Fort of thermo-fluid sciences rests on three
  pillars
• Thermodynamics,
• Fluid mechanics,
• Heat transfer.
• Fluid mechanics principles are involved in open
  system thermodynamics processes.
• They play a primary role in every convective
  heat transfer problem.

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A Superior Method of Problem Solving

• A Pedagogy to turn a science student into
  engineering student.
• The corner stone of this subject is introduction
  of the framework of conservation and accounting.
• All Fluid Flows are Viscous in reality.
• One need to Pay To sustain Fluid Flow.
• Pragmatic way of learning Usage of
  conservation laws.
• Collection of some fundamental physical variables
  which naturally show the behavior of conservation
  and amicable for accounting.
• Develop pseudo variables which can be cast into
  this frame work for better problem solving. (May
  be very difficult.!)

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In Modern Era

• An Essential Engineering Science for All
  Thermo-fluid Processes.
• A Novel Science created by applying of Laws of
  conservation to a Control Volume.
• Creation of devices by manipulation of scalar
  vector fields using a system of tensors.
• Describes a class of Thermo-fluid systems.

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21st Century Made Fluid Mechanics as Universal
Engineering Tool.
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Fluid Flows in Transportation Sector
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Environmental Fluid Flows
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Weather Fluid Flows
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Biological Fluid Flows
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Knowledge of Viscous Fluid Flow for Design of
Artificial Heart Valves
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Fluid Flows for Sports
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Development of Fluid Flow Systems using a
selected combination of Forces

• Systems only due to Body Forces.
• Systems due to only normal surface Forces.
• Systems due to both normal and tangential surface
  Forces.
• Only mechanical forces.
• Only electrical forces.
• Electro-kinetic forces.
• Thermo-dynamic Effects (Buoyancy forces/surface
  )..
• Physico-Chemical/concentration based forces
  (Environmental /Bio Fluid Mechanics

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Major Flow Systems due to Mechanical Forces
Level 1

• Incompressible A vector dominated..
• Compressible Both vector and scalar .

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1930s Flying StoryCruising at High Altitudes
?!?!?!

• Aircraft were trying to approach high altitudes
  for a better fuel economy.
• This led to numerous crashes for unknown reasons.
  
• These included
• The rapidly increasing forces on the various
  surfaces, which led to the aircraft becoming
  difficult to control to the point where many
  suffered from powered flight into terrain when
  the pilot was unable to overcome the force on the
  control stick.
• The Mitsubishi Zero was infamous for this
  problem, and several attempts to fix it only made
  the problem worse.
• In the case of the Super-marine Spitfire, the
  wings suffered from low torsional stiffness.

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• The P-38 Lightning suffered from a particularly
  dangerous interaction of the airflow between the
  wings and tail surfaces in the dive that made it
  difficult to "pull out.
• Flutter due to the formation of thin high
  pressure line on curved surfaces was another
  major problem, which led most famously to the
  breakup of de Havilland Swallow and death of its
  pilot, Geoffrey de Havilland, Jr.

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The Jet Plane Vampire

• The first to exceed a speed of 500 miles per
  hour.
• A total of 3,268 Vampires were built in 15
  versions, including a twin-seat night fighter,
  trainer and a carrier-based aircraft designated
  Sea Vampire.
• DH108 was a newer version was built and released
  for test.

• Initially DH 108 behaved very nicely.
• As the speed was stepped up in was unsuspectingly
  drawn closer to an invisible wall in the sky.
• It was unknown to anyone.
• One evening the pilot hit this wall and the plane
  was disappered.