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SUMMARY:The scaling of the drag force on an accelerating plate - Jerry Wes
 terweel\, TU Delft
DTSTART:20240503T150000Z
DTEND:20240503T160000Z
UID:TALK216292@talks.cam.ac.uk
CONTACT:Professor Grae Worster
DESCRIPTION:The drag force on an accelerating object is usually described 
 by a quasi-steady force that scales with the square of the instantaneous v
 elocity and an added mass force due to the acceleration that scales direct
 ly proportional to the acceleration. This appears to underestimate the exp
 erimentally observed instantaneous drag force on an accelerating plate. We
  aim to find a better description of the drag force on a flat plate in an 
 unsteady flow by measuring both the drag force and velocity field for a la
 rge range of constant accelerations and velocities. Our experiments show t
 hat the force due to acceleration scales with the square root of the accel
 eration\, contrary to a linear scaling that is expected from added mass. T
 his can be associated with a history force that describes the generation a
 nd advection of vorticity at the plate surface. We present a new scaling l
 aw for the drag force on accelerating plates. This avoids previous inconsi
 stencies in using added mass forces in the description of forces on accele
 rating plates. This new scaling law has proven useful in predicting the dr
 ag force for different plate geometries and non-constant accelerations.
LOCATION:MR2
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