Citation
Noca, Flavio (1997) On the evaluation of timedependent fluiddynamic forces on bluff bodies. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd08102005132659
Abstract
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We present some exact expressions for the evaluation of timedependent forces on a body in an incompressible and viscous crossflow which only require the knowledge of the velocity field (and its derivatives) in a finite and arbitrarily chosen region enclosing the body.
Given a control volume V with external surface S which encloses an arbitrary body, the fluiddynamic force F on the body can be evaluated from one of the following three expressions (in abbreviated form):
F = [...] + body motion terms,
F = [...] + body motion terms,
F = no volume integral terms + [...] + body motion terms,
where N is the space dimension, u is the flow velocity, [...] is the vorticity, x is the position vector, and the tensors [...], [...], [...] depend only on the velocity field u and its (spatial and temporal) derivatives.
The first equation is already known for either simply connected domains or inviscid flows. We rederive it here for viscous flows in doubly connected domains (i.e. domains which include a body). We then obtain the second and third equation through a simple algebraic manipulation of the first equation.
These expressions are particularly useful for experimental techniques like Digital particle Image Velocimetry (DPIV) which provide time sequences of 2D velocity fields but not pressure fields.
They are tested experimentally with DPIV on twodimensional, low Reynolds number circular cylinder flows. Both steady and unsteady motions are studied.
Item Type:  Thesis (Dissertation (Ph.D.)) 

Subject Keywords:  Aerodynamic; bluff; DPIV; flow; fluid; forces; hydrodynamic; impulse; momentum; PIV; pressure; velocity; vorticity 
Degree Grantor:  California Institute of Technology 
Division:  Engineering and Applied Science 
Major Option:  Aeronautics 
Thesis Availability:  Public (worldwide access) 
Research Advisor(s): 

Thesis Committee: 

Defense Date:  20 May 1997 
Record Number:  CaltechETD:etd08102005132659 
Persistent URL:  http://resolver.caltech.edu/CaltechETD:etd08102005132659 
Default Usage Policy:  No commercial reproduction, distribution, display or performance rights in this work are provided. 
ID Code:  3081 
Collection:  CaltechTHESIS 
Deposited By:  Imported from ETDdb 
Deposited On:  10 Aug 2005 
Last Modified:  26 Dec 2012 02:56 
Thesis Files

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