differential equation, Mathematics

Assignment Help:
Suppose a fluid (say, water) occupies a domain D? R^(3 ) and has velocity field V=V(x, t). A substance (say, a day) is suspended into the fluid and will be transported by the fluid as well as diffused within it; let u= u(x,t) be the concentration of the substance( mass per unit volume). Let Ø= Ø(x,t) be the concentration flux (mass per unit area per unit time, analogous to heat flux). Let B(x) be a ball of radius r > 0 contained in D. Derive the conservation law.

?_(B (x))¦u_(t ) dV= -?_(? B(x))¦?Ø.n_0 dS.?

Fick''s law for diffusion states that the concentration flux due to diffusion is proportional to the gradient of the concentration flux due to diffusion is proportional to the gradient of the concentration. Deduce that Ø= -k?+uV.
Apply the divergence theorem to the conservation law and substitute the flux formula to arrive at the diffusion- transport equation:
u_t= ?.(k?u)+ ?.(uV).
in the absence of diffusion (k=0), this is the higher- dimensional transport equation. If the fluid is motionless, it is called the diffusion equation.
Suppose a fluid (say, water) occupies a domain D? R^(3 ) and has velocity field V=V(x, t). A substance (say, a day) is suspended into the fluid and will be transported by the fluid as well as diffused within it; let u= u(x,t) be the concentration of the substance( mass per unit volume). Let Ø= Ø(x,t) be the concentration flux (mass per unit area per unit time, analogous to heat flux). Let B(x) be a ball of radius r > 0 contained in D. Derive the conservation law.

?_(B (x))¦u_(t ) dV= -?_(? B(x))¦?Ø.n_0 dS.?

Fick''s law for diffusion states that the concentration flux due to diffusion is proportional to the gradient of the concentration flux due to diffusion is proportional to the gradient of the concentration. Deduce that Ø= -k?+uV.
Apply the divergence theorem to the conservation law and substitute the flux formula to arrive at the diffusion- transport equation:
u_t= ?.(k?u)+ ?.(uV).
in the absence of diffusion (k=0), this is the higher- dimensional transport equation. If the fluid is motionless, it is called the diffusion equation.

Related Discussions:- differential equation

Quadric surfaces, identify 4 sketch the quadric surfaces

identify 4 sketch the quadric surfaces

Definition of random variables, Q. Definition of Random Variables? Ans...

Q. Definition of Random Variables? Ans. Up to this point, we have been looking at probabilities of different events. Basically, random variables assign numbers to element

Example of a function - inflection point, 1. (a) Give an example of a funct...

1. (a) Give an example of a function, f(x), that has an inflection point at (1, 4). (b) Give an example of a function, g(x), that has a local maximum at ( -3, 3) and a local min

Word problems involving money, Word Problems Involving Money: The prom...

Word Problems Involving Money: The promoter of a track meet engages a 6,000 seat armory.  He needs to gross $15,000. The price of children's tickets is to be one-half the pric

Calculate the radius of the circle, In the figure, ABCD is a square inside ...

In the figure, ABCD is a square inside a circle with centre O. The Centre of the square coincides with O & the diagonal AC is horizontal of AP, DQ are vertical & AP = 45 cm, DQ = 2

Geometria, un prisma retto ha per base un rombo avente una diagonale lunga ...

un prisma retto ha per base un rombo avente una diagonale lunga 24cm. sapendo che la superficie laterale e quella totale misurano rispettivamente 2800cm e3568cm ,calcola la misura

Find the function and domain, Consider the function f(x) = x + 1/x 2 + 2x ...

Consider the function f(x) = x + 1/x 2 + 2x - 3. (a) Find f(2) and f(-2). (b) Find the domain of f(x). (c) Does the range include 1? Show your working. (d) Find and si

Determine the second derivative of q (t ) = sec (5t ), Determine the secon...

Determine the second derivative for following functions.                             Q (t ) = sec (5t ) Solution : Following is the first derivative.              Q′ (t

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd