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SUMMARY:&quot\;Modelling the flight of wind borne debris&quot\; - Dr David
  Hargreaves - University of Nottingham
DTSTART:20110304T150000Z
DTEND:20110304T160000Z
UID:TALK30152@talks.cam.ac.uk
CONTACT:Lorna Everett
DESCRIPTION:Windborne debris can be described as failed building component
 s\, loose items and street furniture that are picked up and carried by the
  wind during severe storms.  Studies of building performance during storms
  have identified windborne debris as the principle cause of building failu
 re and as an essential component of the debris damage chain.  The present 
 work focuses on plate type debris - roofing sheets\, shingles and tiles - 
 the dominant type in a residential setting.\n\nCurrent debris risk and dam
 age models often include analytical models of debris flight\, based around
  six degree-of-freedom (6DOF) models.  Many of these models assume aerodyn
 amic coefficients which are obtained from time-averaged wind tunnel measur
 ements on static\, inclined plates.  These coefficients are then modified 
 to take into account unsteady and non-linear\, fluid-structure interaction
 s by means of various empirical coefficients.  While successful in certain
  circumstances\, these quasi-steady coefficients produce inaccuracies in t
 he analytical models.\n\nThe present work uses a 3D Computational Fluid Dy
 namics (CFD) model\, which is sequentially coupled with a 6DOF rigid body 
 dynamics (RBD) model to simulate the flight of plates in high Reynolds num
 ber flow.  The idea\, using this computationally demanding approach\, is t
 o better understand the mechanics of the flight and to derive more reliabl
 e aerodynamic coefficients for use in simpler models.\n\nThe commercial CF
 D software\, ANSYS-Fluent\, has been used throughout but the default RDB m
 odel\, based on the Euler rotational matrix approach\, has been replaced b
 y a singularity-free method based on rotational quaternions.  The model ha
 s been used to investigate the influence of plate initial orientation on t
 he flight trajectories.  Different flight modes are identified\, depending
  on the initial conditions\, with a clear transition between different mod
 es being demonstrated.\n\n\n
LOCATION:Engineering Department - **LR6**
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