Boundary Conditions

In the preceding section, differential equations were given for three types of prob­lems. In order to solve these equations, we need to define boundary and initial con­ditions. Classical boundary conditions may be considered: imposed displacements or forces for solid mechanics problems and imposed fluid pressures, temperatures, concentrations or fluxes for diffusion and advection-diffusion problems.

However, it may be useful to consider much more complex boundary conditions. For example, in solid mechanics, unilateral contact with friction or interface be­haviour is often to be considered.

When coupling phenomena, the question of boundary conditions increases in complexity and has to be discussed.