Surface for low drag in turbulent flow
Patent 5114099 Issued on May 19, 1992. Estimated Expiration Date: 
June 4, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
June 4, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 1454479 1726882 2608171 2800291 2899150 3184184 3213819 Driven craft having surface means for increasing propulsion efficiencies Airstream modification device for airfoils Low drag surface InventorAssigneeApplicationNo. 532864 filed on 06/04/1990US Classes:244/130, Aerodynamic resistance reducing244/200By characteristic of airfoil's skinExaminersPrimary: Peters, Joseph F. Jr.Assistant: Mattix, Carla Attorney, Agent or FirmForeign Patent References
International ClassB64C 021/10AbstractA nonsmooth surface of an object in a fluid flowstream permits a reduction of turbulent drag. The surface shape is designed to approximate a minimal surface and satisfies the equation (V⋅∇)∇Φ=0, where V is the relative velocity between the fluid and the surface, ∇Φ is the velocity of the strain tensor. The improved surface shape may be an array of diamond shaped elements having an airfoil like diagonal along the streamline, or it may be a series of wavelets juxtaposed to one another. The specific shape of the various types of elements to be used on the surface is selected based upon the acceleration or deceleration of the fluid at the particular position on the surface, as well as the intensity of the turbulence at that position.Other References
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