Law of Laplace
The original law of Laplace pertains to soap bubbles, with radius r, and gives the relation between transmural pressure, P t , and wall tension, T s , in a thin-walled sphere as T s =P t · r. The law can be used, for example, to calculate tension in alveoli. This tension is directly related to surface tension and has the dimension N/m. The form of the law of Laplace most often used in hemodynamics gives the relation between transmural pressure and the stress in the wall in organs with a wall thickness h. We here use the Cauchy stress formulation, which is defined as the ratio of the normal (perpendicular) force acting on a surface divided by the area of the surface at its deformed configuration. Stress has the dimension N/m2 (see Figure in the box).
KeywordsCircular Cylinder Fiber Stress Wall Stress Transmural Pressure Wall Tension
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