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A liquid hitting a wall in a container will cause sloshing. The free surface effect is a mechanism which can cause a watercraft to become unstable and capsize. [1]It refers to the tendency of liquids — and of unbound aggregates of small solid objects, like seeds, gravel, or crushed ore, whose behavior approximates that of liquids — to move in response to changes in the attitude of a craft ...
Important examples include propellant slosh in spacecraft tanks and rockets (especially upper stages), and the free surface effect (cargo slosh) in ships and trucks transporting liquids (for example oil and gasoline). However, it has become common to refer to liquid motion in a completely filled tank, i.e. without a free surface, as "fuel slosh".
Here σ is the surface tension, n, t and s are unit vectors in a local orthogonal coordinate system (n,t,s) at the free surface (n is outward normal to the free surface while the other two lie in the tangential plane and are mutually orthogonal). The indices 'l' and 'g' denote liquid and gas, respectively and K is the curvature of the free surface.
Damage stability calculations are much more complicated than intact stability. Software utilizing numerical methods are typically employed because the areas and volumes can quickly become tedious and long to compute using other methods. The loss of stability from flooding may be due in part to the free surface effect.
In computational fluid dynamics, free-surface modelling (FSM) refers to the numerical modelling of a free surface—a freely moving interface between immiscible fluids—in order to be able to track and locate it. Common methods used in free surface modelling include the level-set method and the volume of fluid method
Flatness refers to the shape of a liquid's free surface. On Earth, the flatness of a liquid is a function of the curvature of the planet, and from trigonometry, can be found to deviate from true flatness by approximately 19.6 nanometers over an area of 1 square meter, a deviation which is dominated by the effects of surface tension.
Once a solution (i.e. the horizontal velocities and free surface displacement) has been found, the vertical velocity can be recovered via the continuity equation. Situations in fluid dynamics where the horizontal length scale is much greater than the vertical length scale are common, so the shallow-water equations are widely applicable.
The surface energy of a liquid may be measured by stretching a liquid membrane (which increases the surface area and hence the surface energy). In that case, in order to increase the surface area of a mass of liquid by an amount, δA, a quantity of work, γ δA, is needed (where γ is the surface energy density of the liquid).