University of Utah

Department of Mathematics

Math 3150-001   Partial Differential Equations for Engineers
T,  M.W.       10:45 - 11:35 am     WEB L110

Textbook:   Partial Differential Equations and Boundary Value Problems, N. Asmar, Prentice Hall 2005; Second Edition
Sections: 1.1, 1.2; 2.1 - 2.4; 3.1 - 2.9; 4.1 - 4.4; 7.1 - 7.4

Instructor:   Andrej Cherkaev
Office: JWB 225   ph: 581-6822   email:cherk@math.utah.edu
Office hours: F, 10-12 and by appointment


About the subject:
Partial differential equations (PDE) are a type of differential equation, i.e., a relation involving an unknown function (or functions) of several independent variables and their partial derivatives with respect to those variables. PDEs are used to formulate, and thus aid the solution of problems involving functions of several variables.

PDEs are for example used to describe the propagation of sound or heat, electrostatics, electrodynamics, Fuid flow, and elasticity. These seemingly dis- tinct physical phenomena can be formalized identically (in terms of PDEs), which shows that they are governed by the same underlying dynamic. PDEs fnd their generalization in stochastic partial di erential equations. Just as orinary differential equations often model dynamical systems, partial di erential equations often model multidimensional systems.
     Wikipedia: Partial differential equation


Student Solutions Manual 
can be downloaded from the author's website:
http://www.math.missouri.edu/~nakhle/pdebvp/student-manual.pdf

Tutoring is available in T. Benny Rushing Mathematics Center

Syllabus is here

Home work
HW1. Section 1.2: Problems 5, 11, 16. Section 2.1: Problems 2, 9, 12, 14, 19.
HW2. Section 2.2: Problems 5, 11, 15. Section 2.3: Problems 4, 17. (You may use Maple)
HW3. Section 2.3: Problems 2, 9, 17. Section 2.4: Problems 4, 16.
HW4. Section 3.3: Problems 1, 9, 11. Section 3.4: Problem 2.
HW5. Section 3.5: Problems 2, 4, 12. Section 3.6: Problems 2, 5, Section 3.7: Problems 1, 2.

HW 6. Section 3.8: Problem 4. (Graph the solution). Section 3.9: Problems 3, 7 Example: Maple code for Fourier series calculations
# Example of computing Fourier series (Ch. 2)

# 1. Set the periodic function f and period p
f := x - exp(x);
p := 1;

# 2. Compute Fourier coefficients:
a0 := (int(f, x = -p .. p))/(2 p);
an := (int(f*cos(n*Pi*x/p), x = -p .. p))/p;
bn := (int(f*sin(n*Pi*x/p), x = -p .. p))/p;

# 3. Compute the partial sum fn (Here, n=15)
fn := a0+sum(an*cos(n*Pi*x/p)+bn*sin(n*Pi*x/p), n = 1 .. 15);

# 4. Plot the function, the partial sum, and their difference
plot({f, fn}, x = -p .. p);
plot(f-fn, x = -p .. p);

# 5. Repeat for any function and any period.


HW 7. Section 4.1: Problems 3, 6. Section 4,2: Problems 2. Bonus Problem 10

Hints for Bessel functions (Maple)

Plot of Bessel functions

plot(BesselJ(0, x), x=0 .. 30);
plot(BesselJ(1, x), x=0 .. 30);

First zeros of Bessel Function:

z1 := evalf(BesselJZeros(0, 1));
z2 := evalf(BesselJZeros(0, 2));
z3 := evalf(BesselJZeros(0, 3));
etc.

Alternatively, one can compute them at once:

> for n to 10 do w[n] := evalf(BesselJZeros(0, n)) end do;
2.404825558
5.520078110
8.653727913
11.79153444
14.93091771
18.07106397
21.21163663
24.35247153
27.49347913
30.63460647

Computing coefficients of Bessel Series. f is an arbitrary function: Here I put a=1

f := 100-r;

Notice, to perform numerical intergation in Maple I put the upper limit in the form a=1.0 (floating point)

for n to 10 do A[n] := 2*(int(f*BesselJ(0, w[n]*r)*r, r = 0 .. 1.0))/BesselJ(1, w[n]) end do;
0.4072812946
-0.02337240050
0.01441795517
-0.004036123910
0.003507320274
-0.001467399340
0.001418570623
-0.0007181654672

The summarion of Bessel Series, Example c=2

u := sum(A[k]*BesselJ(0, w[k]*r)*cos(2*w[k]*t), k = 1 .. 10);

Plotting

plot3d(u, r=0 .. 1, t=0 .. 2, axes=boxed);
animate(plot, [u, r=0 .. 1], t=0 .. 3);