Boundary layer flow velocity is greater for thicker films. A surface wave catches up with, and collects more fluid from thinner films, until it builds into a breaking wave, that rushes across the wet surface.binbagsss said:
in terms of the equations sorry, not physically, thanksBaluncore said:
Which situation and which equations.binbagsss said:
A free surface flow is a type of fluid flow where the fluid has a free surface exposed to the atmosphere, such as water flowing in an open channel, river, or ocean. This surface can deform and move in response to forces, unlike confined flows where the fluid is completely enclosed by solid boundaries.
The free surface introduces non-linearity because its shape and position can change dynamically in response to the flow conditions. This creates a feedback loop where the flow affects the surface, and the surface, in turn, affects the flow. This interaction leads to complex behaviors such as waves, turbulence, and varying flow velocities, which are inherently non-linear.
Examples of non-linear phenomena in free surface flows include wave breaking, the formation of vortices, hydraulic jumps, and the development of complex patterns such as ripples and eddies. These phenomena arise due to the interactions between the fluid motion and the changing free surface.
Modeling free surface flows is challenging because the equations governing the flow (such as the Navier-Stokes equations) become highly complex when accounting for the moving and deforming free surface. Additionally, the boundary conditions at the free surface are non-linear and time-dependent, making analytical solutions difficult and often necessitating advanced numerical methods for accurate simulations.
Engineers and scientists study non-linearity in free surface flows using a combination of theoretical analysis, laboratory experiments, and numerical simulations. They employ tools such as computational fluid dynamics (CFD) to model the flow and predict behaviors. Experimental setups, such as wave tanks and flumes, are also used to observe and measure the physical phenomena directly, providing data to validate and refine models.