hi, i have a few basic questions with reference to different pdes we come across in CFD (viz. hyperbolic, parabolic and elliptic pdes) 1)can somebody please suggest a phenomenon which is strictly parabolic or elliptic or hyperbolic. 2)hyperbolic pdes are characterised by direction dependence.does this mean that they vary only in space. 3)parabolic pdes are characterised by variation in only one co-ordinate.does this mean that they vary only in time.if no, what is the difference between hyperbolic and parabolic pdes. 3)how do differentiate mathematically between different pdes for first order equations(we cannot use the discriminant here which are defined only for 2nd order equations).

i would be grateful if somebody may answer these queries.

with regards shiva

Basically the types are

Parabolic equations describe diffusion type problems (heat equation),

Hyperbolic equations are wavelike (the wave equation) and

Elliptic are for steady state type behaviour (Laplaces equation)