Partial Differential Equations
www.math.toronto.edu › ivrii › PDE-textbookA partial di erential equation is an equation for a function which depends on more than one independent variable which involves the independent variables, the function, and partial derivatives of the function: F(x;y;u(x;y);u x(x;y);u y(x;y);u xx(x;y);u xy(x;y);u yx(x;y);u yy(x;y)) = 0: This is an example of a PDE of order 2. Solving an equation like this
Solving partial differential equations (PDEs)
www.southampton.ac.uk › ~fangohr › teaching2d Di usion equation @u @t = D @2u @x2 + @2u @y2 u(t;x;y) is the concentration [mol/m3] tis the time [s] xis the x-coordinate [m] yis the y-coordinate [m] D is the di usion coe cient [m2/s] Also known as Fick’s second law. The heat equation has the same structure (and urepresents the temperature). Example: http://www.youtube.com/watch?v=WC6Kj5ySWkQ 5/47