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In fluid dynamics, the Basset–Boussinesq–Oseen equation (BBO equation) describes the motion of – and forces on – a small particle in unsteady flow at low Reynolds numbers. The equation is named after Joseph Valentin Boussinesq, Alfred Barnard Basset and Carl Wilhelm Oseen. ==Formulation== One formulation of the BBO equation is the one given by , for a spherical particle of diameter , position and mean density moving with particle velocity – in a fluid of density , dynamic viscosity and with ambient (undisturbed local) flow velocity 〔With referring to 〕 : This is Newton's second law, with in the left-hand side the particle's rate of change of linear momentum, and on the right-hand side the forces acting on the particle. The terms on the right-hand side are respectively due to the: # Stokes' drag, # pressure gradient, with the gradient operator, # added mass, # Basset force and # other forces on the particle, such as due to gravity, etc. The particle Reynolds number : has to be small, , for the BBO equation to give an adequate representation of the forces on the particle. Also suggest to estimate the pressure gradient from the Navier–Stokes equations: : with the material derivative of Note that in the Navier–Stokes equations is the fluid velocity field, while in the BBO equation is the undisturbed fluid velocity at the particle position: 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Basset–Boussinesq–Oseen equation」の詳細全文を読む スポンサード リンク
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