2. Consider the 'Robin problem', defined as: solve the inhomogeneous heat equation du + s(r, 1), for 0 0, with initial/boundary conditions u(r,0) = uo(z), u(0,t)- au, (0,t) s(). u(L, t) + Bu, (0, t) = 9(4) r>0 t>0 t>0 where a, 320 (a) Show that if u,(x,t) and u(r, t) are two solution of the Robin problem then their difference w(x,t) = u(1,t)- ua(r,t) satisfies the homogeneous heat equation with all initial/boundary conditions replaced by their homogeneous counterparts. (b) Define the energy of a solution w(z, t) of the homogeneous heat equation by E(t) = | w*(r,t) dz. Prove that E'() = -aw,"(0, t) - Bu,"(L, t)- (c) Deduce that w(r, t) as defined in part (a) must vanish identically so the Robin problem has a unique solution.

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
Question
3
2. Consider the 'Robin problem', defined as: solve the inhomogeneous heat equation
u
+ s(r, t),
du
for 0 <z < L
where o > 0, with initial/boundary conditions
u(r,0) = uo(r),
I>0
u(0, t) – au, (0, t) = f(t),
u(L, t) + Bu, (0, t) = g(t)
t>0
t>0
where a, 320
(a) Show that if u (z, t) and u2(r, t) are two solution of the Robin problem then their difference
w(r, t) = u(x, t) – uz(r, t) satisfies the homogeneous heat equation with all initial/boundary
conditions replaced by their homogeneous counterparts.
(b) Define the energy of a solution w(r, t) of the homogeneous heat equation by
E(t) = ! | w*(x, t) dr.
Prove that
E'() = -aw,"(0,t) - Bu,"(L, t) - ow(a,t) dr.
(c) Deduce that w(r, t) as defined in part (a) must vanish identically so the Robin problem has a
unique solution.
Transcribed Image Text:2. Consider the 'Robin problem', defined as: solve the inhomogeneous heat equation u + s(r, t), du for 0 <z < L where o > 0, with initial/boundary conditions u(r,0) = uo(r), I>0 u(0, t) – au, (0, t) = f(t), u(L, t) + Bu, (0, t) = g(t) t>0 t>0 where a, 320 (a) Show that if u (z, t) and u2(r, t) are two solution of the Robin problem then their difference w(r, t) = u(x, t) – uz(r, t) satisfies the homogeneous heat equation with all initial/boundary conditions replaced by their homogeneous counterparts. (b) Define the energy of a solution w(r, t) of the homogeneous heat equation by E(t) = ! | w*(x, t) dr. Prove that E'() = -aw,"(0,t) - Bu,"(L, t) - ow(a,t) dr. (c) Deduce that w(r, t) as defined in part (a) must vanish identically so the Robin problem has a unique solution.
2. Consider the 'Robin problem', defined as: solve the inhomogeneous heat equation
u
+ s(r, t),
du
for 0 <z < L
where o > 0, with initial/boundary conditions
u(r,0) = uo(r),
I>0
u(0, t) – au, (0, t) = f(t),
u(L, t) + Bu, (0, t) = g(t)
t>0
t>0
where a, 320
(a) Show that if u (z, t) and u2(r, t) are two solution of the Robin problem then their difference
w(r, t) = u(x, t) – uz(r, t) satisfies the homogeneous heat equation with all initial/boundary
conditions replaced by their homogeneous counterparts.
(b) Define the energy of a solution w(r, t) of the homogeneous heat equation by
E(t) = ! | w*(x, t) dr.
Prove that
E'() = -aw,"(0,t) - Bu,"(L, t) - ow(a,t) dr.
(c) Deduce that w(r, t) as defined in part (a) must vanish identically so the Robin problem has a
unique solution.
Transcribed Image Text:2. Consider the 'Robin problem', defined as: solve the inhomogeneous heat equation u + s(r, t), du for 0 <z < L where o > 0, with initial/boundary conditions u(r,0) = uo(r), I>0 u(0, t) – au, (0, t) = f(t), u(L, t) + Bu, (0, t) = g(t) t>0 t>0 where a, 320 (a) Show that if u (z, t) and u2(r, t) are two solution of the Robin problem then their difference w(r, t) = u(x, t) – uz(r, t) satisfies the homogeneous heat equation with all initial/boundary conditions replaced by their homogeneous counterparts. (b) Define the energy of a solution w(r, t) of the homogeneous heat equation by E(t) = ! | w*(x, t) dr. Prove that E'() = -aw,"(0,t) - Bu,"(L, t) - ow(a,t) dr. (c) Deduce that w(r, t) as defined in part (a) must vanish identically so the Robin problem has a unique solution.
Expert Solution
steps

Step by step

Solved in 4 steps

Blurred answer
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,