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Free surface deformation
Posted Jan 19, 2010, 7:37 a.m. EST 1 Reply
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Hello Folks,
imagine a drilling (2mm in diameter) in a plane. The drilling is filled with a fluid, lets say, water, the surrounding fluid is air. All material data can be loaded from the Comsol material data base. The temperature shall be just room temperature. From the bottom of the drilling a pressure shall be applied that way, that it squeezes out the water slowly not breaking the surface tension of the water-air boundary layer. Consequently a spherical surface develops from the round edge of the drilling. An static state is reached when the applied pressure is equal the gravity force caused by the sperical-pig (water).
Here is the question: how can this process be simulated? which is the best mode? I tried to adapt the 'droplet brak-up in a t-junction' example which seems to handle quite similar problems but it lead nowhere so far.
www.comsol.com/showroom/gallery/1994/
Also I tried a 2D 2phase level-set simulation but unfortuately didn't succeed.
Has anyone an idea how to simulate that process and mesh the model respectively adjust the numerical parameters right? I am very thankful for help.
imagine a drilling (2mm in diameter) in a plane. The drilling is filled with a fluid, lets say, water, the surrounding fluid is air. All material data can be loaded from the Comsol material data base. The temperature shall be just room temperature. From the bottom of the drilling a pressure shall be applied that way, that it squeezes out the water slowly not breaking the surface tension of the water-air boundary layer. Consequently a spherical surface develops from the round edge of the drilling. An static state is reached when the applied pressure is equal the gravity force caused by the sperical-pig (water).
Here is the question: how can this process be simulated? which is the best mode? I tried to adapt the 'droplet brak-up in a t-junction' example which seems to handle quite similar problems but it lead nowhere so far.
www.comsol.com/showroom/gallery/1994/
Also I tried a 2D 2phase level-set simulation but unfortuately didn't succeed.
Has anyone an idea how to simulate that process and mesh the model respectively adjust the numerical parameters right? I am very thankful for help.
1 Reply Last Post Jan 19, 2010, 12:27 p.m. EST
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Posted:
1 decade ago
If dynamic effects are not important then what you really want is a sequence of equilibrium shapes for the free surface as a function of displacement volume subject to boundary conditions (prescribed contact angle or fixed contact line).
The shape of such an interface is mathematically represented through a nonlinear PDE that balances surface tension pressure against hydrostatic pressure (due to gravity) subject to boundaery conditions and a volume constraint (to account for displacement). Derive or look up that equation and solve it using one of the equation forms. Just as an example, in the special case of a an axisymmetric sessile drop that is so small that the gravity is un-important (you can check this by calculating the gravitational Bond number), the shape is given as a spherical section and the pressure inside the drop can be calculated from the Young-Laplace equation.
You won't need to worry about level sets etc for this.
The shape of such an interface is mathematically represented through a nonlinear PDE that balances surface tension pressure against hydrostatic pressure (due to gravity) subject to boundaery conditions and a volume constraint (to account for displacement). Derive or look up that equation and solve it using one of the equation forms. Just as an example, in the special case of a an axisymmetric sessile drop that is so small that the gravity is un-important (you can check this by calculating the gravitational Bond number), the shape is given as a spherical section and the pressure inside the drop can be calculated from the Young-Laplace equation.
You won't need to worry about level sets etc for this.