To handle a PDE with two Laplacian terms in COMSOL Multiphysics using the PDE interface, define the equation explicitly in the Equation-Based Modeling section. Include the Laplacian terms using the built-in laplacian operator (e.g., D1⋅laplacian(u) and D2⋅laplacian(v). Specify dependent variables, boundary conditions, and initial conditions, then mesh and solve the model. COMSOL’s postprocessing tools can visualize the results for uu and vv. This approach ensures accurate handling of systems with multiple Laplacian terms.

Thank you for your help. I have one more question. How to calculate strain energy in Laminar Flow module of comsol. In particular for non-newtonian fluid case.

In COMSOL Multiphysics, handling two Laplacian terms in a Partial Differential Equation (PDE) within the Equation-Based Modeling interface can be done by directly specifying the equation with the Laplacian terms. Here's a step-by-step approach:

By setting up the terms for the Laplacians manually in this way, COMSOL will treat the equation with two Laplacian terms and solve it accordingly.