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SUMMARY:Numerical Simulations of Deflagration to Detonation Transitions - 
 Nikos Nikiforakis (Centre for Scientific Computing\, Cambridge)
DTSTART:20091110T163000Z
DTEND:20091110T173000Z
UID:TALK20837@talks.cam.ac.uk
CONTACT:Sally Hales
DESCRIPTION:Combustible mixtures of gases can support two steady modes of 
 combustion\, namely deflagration and detonation.  Under certain conditions
  a relatively low speed deflagration can accelerate to form a supersonic d
 etonation wave\, a process referred to as deflagration to detonation trans
 ition (DDT).  Whilst the behaviour of study deflagrations and detonations 
 is reasonably well understood\, there are many gaps in our understanding o
 f the nature of the transition mechanism.  The aim of this research is to 
 investigate the transition process\, i.e. the reasons behind the change of
  propagation mechanism from the advection/reaction/diffusion mode of a def
 lagration\, to the coupled shock/reaction system of a detonation wave and 
 in particular the role of interfacial instabilities.  To this end\, the ef
 fect of the Richtmyer-Meshkov instability arising from the interaction of 
 a shock wave with a flame has been investigated.  Transition to detonation
  is shown to take place in the neighbourhood of localised temperature pert
 urbations (hot-spots). Finally\, the character of the interim combustion-d
 riven waves arising from these hot-spots is analysed.  Aspects related to 
 the formulation and the numerical solution (numerical schemes and adaptive
  mesh refinement) will also be discussed.\n
LOCATION:Martin Ryle Seminar Room\, Kavli Building
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