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In the design of fluid bearings, the Sommerfeld number (S), or bearing characteristic number, is a dimensionless quantity used extensively in hydrodynamic lubrication analysis. The Sommerfeld number is very important in lubrication analysis because it contains all the variables normally specified by the designer. The Sommerfeld number is named after Arnold Sommerfeld (1868–1951). ==Definition== The Sommerfeld Number is typically defined by the following equation.〔Shigley 1989, p.484.〕 : Where: : S is the Sommerfeld Number or bearing characteristic number : ''r'' is the shaft radius : ''c'' is the radial clearance : ''µ''; is the absolute viscosity of the lubricant : ''N'' is the speed of the rotating shaft in rev/s : ''P'' is the load per unit of projected bearing area However, an alternative definition is used in some texts based on angular velocity:〔Williams, J. 1994. Engineering Tribology. p267.〕 : Where: : is angular velocity of the shaft in rad/s. : ''W'' is the applied load : ''L'' is the bearing length : ''D'' is the bearing diameter It is therefore necessary to check which definition is being used when referring to design data or textbooks, since the value of S will differ by a factor of 2π. 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「Sommerfeld number」の詳細全文を読む スポンサード リンク
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