Hi I would like to calculate the shape of a drop in a surface. This is a relatively old problem which solves the Young and Laplace equation ( a PDE ) subject to boundary conditions that includes the contact angle. It has been solved usually with finite element method codes in 3D or ordinary differential equation codes in 2D. My question is, given that the CFD codes are dynamic in nature, is it possible to solve this static problem with such codes?. Can anybody share some experience?

Thanks in advance

Newbie

Do not be put off so much by finite element codes for this class of problems. In particular, for capillary hydrostatic equilibrium problems a Monge representation of surface shape as a function of two independent variables means that your 3D drop shape can be computed with a two dimensional code.

Not all CFD codes require time marching, either. If, however, you're stuck with such a code as the tool for solving a problem like this, then you should still be able to find steady, stable droplet shapes by integrating in time and using viscosity to damp out the oscillations. That presupposes that your CFD code has a reasonable accurate representation for the effects of curvature induced stresses and the kinematic boundary condition at a moving deformable interface.

Finite element formulations have proven an effective front tracking technique for such problems. However, more recent work using level sets, a front capturing approach, is promising and growing in popularity.

Thanks Strangelove, it's very instructive, is it possible for you to give some references about the level sets and front capturing methods? If possible also about codes who implement them. Thanks again

Newbie

Sethian and coworkers have published extensively on level set methods, having done a lot of pioneering work.

He has a nice website that illustrates many basic concepts of the method, as well as having references to his books on the subject.

Literature on other, older front-capturing techniques that you may find interesting include MAC (Marker and Cell), PIC (Particle in Cell) and VOF (Volume of Fluid) approaches.

A search on Google (and on SciSearch®, if you have access to it) for these techniques should provide some leads for finding out more about these techniques.

Commercial codes based on some of these techniques are available: Tony Hirt of VOF fame, for example, has Flow-3D®.

HTH.

Some want can help me? I'm a student, I 've a report of "flow over a cylinder" (solve by ansys), but I dont know where i can get some codes for reference.