SYMBOLS AND DEFINITIONS 



A cross-sectional area of flow over sand bed 



A combined cross-sectional area of cylinders 

 c ' 



A combined cross-sectional area of reservoirs 

 r 



A(Jl) cross-sectional area of flow, a function of Jl 



E total energy 



g acceleration due to gravity 



K time variable part of the kinetic energy 



L length of test section 



I distance along the flow path (see Fig. 3) 



i total flow path length when s = o 



M mass of active counterweight 

 a ^ 



M mass of passive counterweight 



P time variable part of the potential energy 



S amplitude of piston motion (half stroke) 



S maximum amplitude of piston motion (maximum half stroke) 



s displacement of pistons from zero level 



s displacement of free surface in reservoirs from zero level 

 r ^ 



T period of oscillation 



T resonance period when y = o 



t time 



U amplitude of flow velocity in test section 



V magnitude of the velocity vector 



v'(Jl) average velocity over a cross section, a function of £ 



y elevation of the active counterweight when s = o 



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