Question

Where do we encounter partial differential equations in CFD?

(a) Physical models

(b) Assumptions

(c) Governing equations

(d) Discretized equations

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This is a very interesting question from Partial Differential Equation topic in portion Mathematical Behaviour of Partial Differential Equations of Computational Fluid Dynamics

Answer 1

Right choice is (c) Governing equations

The best I can explain: The governing equations of CFD are in partial differential form. This is because the flow variables depend upon four independent variables (three spatial coordinates and one time point). When a flow variable is differentiated with respect to one of the independent variables, the others are kept constant.