kader <fabdelkader@pi.ac.ae> wrote in message <qJWdnbs5kcHhfIHJnZ2dnUU7-a-dnZ2d@giganews.com>... > Hi, > > I`m trying to solve the 1D advection-diffusion-reaction equation dc/dt+u*dc/dx=D*dc2/dx2-kC using Fortan code but I`m still facing some issues. first I solved the advection-diffusion equation without including the source term (reaction) and it works fine. but when including the source term (decay of substence with the fisr order decay -kC)I could not get a correct solution. I have read that I need to use the spliting time mthod or as called also the operator time method, but I do not know how to apply it. > Could any one help to provide a simple code for solving this advection-diffusion-reaction equation ? I would appriciate your help. Try to implement this term kC in time-implicit scheme; i.e. put it in t_(n+1) when solving in (t_n , t_(n+1) ). This scheme is more stable. Bruno

0 |

9/20/2014 7:00:14 AM

You might try to use time-implicit scheme for this term, which is stable and void numerical oscillation.

0 |

9/20/2014 7:53:05 AM

kader <fabdelkader@pi.ac.ae> wrote in message <qJWdnbs5kcHhfIHJnZ2dnUU7-a-dnZ2d@giganews.com>... > Hi, > > I`m trying to solve the 1D advection-diffusion-reaction equation dc/dt+u*dc/dx=D*dc2/dx2-kC using Fortan code but I`m still facing some issues. first I solved the advection-diffusion equation without including the source term (reaction) and it works fine. but when including the source term (decay of substence with the fisr order decay -kC)I could not get a correct solution. I have read that I need to use the spliting time mthod or as called also the operator time method, but I do not know how to apply it. > Could any one help to provide a simple code for solving this advection-diffusion-reaction equation ? I would appriciate your help. > > Regards, > > Kader > Try MATLAB's "pdepe" (at least to check your results) - it uses an implicit method for time integration. Best wishes Torsten.

0 |

9/22/2014 12:45:08 PM

Hi, I`m trying to solve the 1D advection-diffusion-reaction equation dc/dt+u*dc/dx=D*dc2/dx2-kC using Fortan code but I`m still facing some issues. first I solved the advection-diffusion equation without including the source term (reaction) and it works fine. but when including the source term (decay of substence with the fisr order decay -kC)I could not get a correct solution. I have read that I need to use the spliting time mthod or as called also the operator time method, but I do not know how to apply it. Could any one help to provide a simple code for solving this advection-diffusion...

i need to solve this 1D richards equation du/dt = d/dx(D(u)*du/dx)- g where u = u(x,t) D= exp(7*u) g= 100 (constant) in matlab version 6.5 using the forward time centred scheme(FTCS) (not the method of lines) i'm pretty sure the FTCS is u(i,j+1) = u(i,j) + r*(u(i+1,j) + u(1-1,j) - 2*u(i,j)) where r = D*deltat/deltax (deltat and deltax are the grid point spacing between t and x nodes respectively) i'm very new with matlab and i need help with this problem asap In article <b376d0e8.0406112219.1a79e81f@posting.google.com>, agentjonson81@yahoo.com.au (jon) w...

How can I simulate or solve this kind of difference equation? x(k+2)-7x(k+1)+12x(k)=0 A for loop would work nicely. This particular system is unstable. -James Tama Tomi wrote: > How can I simulate or solve this kind of difference equation? > > x(k+2)-7x(k+1)+12x(k)=0 Can you give me a example? James Allison <james.allison@mathworks.com> wrote in message <hmr9fp$62s$1@fred.mathworks.com>... > A for loop would work nicely. This particular system is unstable. > > -James > > Tama Tomi wrote: > > How can I simulate or solve this kind of...

I have a system of equations contains one one-dimensional pde and three ode. Can it be solved by the 'pdepe' solver? If it can,how do I treat the boundary function of odes? ...

New in matlab, Need help please in making a matlab program to solve the wave equation below up to the point when you obtain a system of equations. solve the wave equation below up to the system of equation using Finite difference method utt = c^2 uxx, ut(x,0) = 3sin((pi x)/9) , u(x,0) = 0, U(0,t) = U(4,t) = 0, hx = 1, ht = 0.5, c = 2, nx = 4, nt = 2 nx, hx are number and size of x panels nt, ht are number and size of t panels I am using the Finite difference scheme below u(i,j+1) = c^2*(ht/hx)^2 *(u(i+1,j) + u(i-1,j)) - u(i,j-1) + 2*(1 - c^2*(ht/hx)^2 )*u(i,j) "Kayanja Andy...

I'm doing a fourth year project...Im just starting out and was wondering if anyone would have any suggestions on where to start for this topic.... Melissa wrote: > > > I'm doing a fourth year project...Im just starting out and was > wondering if anyone would have any suggestions on where to start > for > this topic.... Hi GP Agrawal 's book on NL fiber is good start.. Dr. Abhay Kumar > > 4 years? I had to solve this problem in 6 months.... (NLSE + a constitutive equation which correlates the optical field to another physical quantity present i...

hi how can i use matlab to solve equations with my best wishs mido wrote: > hi > how can i use matlab to solve equations > with my best wishs This question needs to be refined a bit. Do you want to solve simultaneous systmes of linear equations? Do you want to solve differential equations? Do you want solve an equations by finding the zeros? Those are just the first few possibilities that come to mind. If I spent a little more time, I'm sure I could come up with another half-dozen (or more) possibilities. That said, I would *strongly* urge you to read the "Getting ...

I have 3 poInts (1,3) (2,1) (1,1 ). From a point (x0,y0), 3 people are walking to 3 different points (1,3) (2,4) (1,4).Assume constant velocity, time they start is unknown say t0. time to reach location1=t0-t1 time to reach location2=t0-t2 time to reach location3=t0-t3 x=[1 2 1]; y=[3 4 4]; syms x0 y0 t0 %Distance from x0,y0 to 1,3 D1=sqrt((x(:,1)-x0)^2+(y(:,1)-y0)^2); %Distance from x0,y0 to 2,1 D2=sqrt((x(:,2)-x0)^2+(y(:,2)-y0)^2); %Distance from x0,y0 to 1,1 D3=sqrt((x(:,3)-x0)^2+(y(:,3)-y0)^2); t0-t1=D1/V; t0-t2=D2/V; t0-t3=D3/V; ...

Hello all hardworking mathematicians! I am trying to solve the diffusion equation given by Fick's law using mathematica. The equation is as follows f = (TAU)*(PHI)*(D12)*(RHOg)*(grad OMEGA) f: mass flux (kg/m2-sec) TAU: Tortuosity - a constant PHI: Porosity - a constant D12: Binary Diffusion Coefficient (m2/sec) RHOg: Density (kg/m3) OMEGA: mass fraction grad: is the gradient operator. As can be seen from the equation, TAU, PHI are physical constants D12: although as time goes and as the gas spreads, this value changes, you can assume it to be constant to start with...

Hi, I wanted to know if there were any inbuilt commands in matlab to solve the equation of the form f(x)=0 numerically. The function f(x) is composed of user written functions. I would really appreciate any help of this as I need it for some urgent work. Thanks. In article <ef26062.-1@webx.raydaftYaTP>, "Apoorva Shende" <apoorvashende@indiatimes.com> wrote: > Hi, I wanted to know if there were any inbuilt commands in matlab to > solve the equation of the form f(x)=0 numerically. The function f(x) > is composed of user written functions. I would really apprecia...

Hello all hardworking mathematicians! I am trying to solve the diffusion equation given by Fick's law using mathematica. The equation is as follows f = (TAU)*(PHI)*(D12)*(RHOg)*(grad OMEGA) f: mass flux (kg/m2-sec) TAU: Tortuosity - a constant PHI: Porosity - a constant D12: Binary Diffusion Coefficient (m2/sec) RHOg: Density (kg/m3) OMEGA: mass fraction grad: is the gradient operator. As can be seen from the equation, TAU, PHI are physical constants D12: although as time goes and as the gas spreads, this value changes, you can assume...

Hi guys I want to solve this kind of equation: a*x + b*y = A (1) a1*x^2 + b1*y^2 = B (2) Thanks in advanced Zhong zhang skrev 2010-01-02 02:17: > Hi guys > > I want to solve this kind of equation: > > a*x + b*y = A (1) > a1*x^2 + b1*y^2 = B (2) > > Thanks in advanced > > Zhong See for example: http://www.mathworks.com/support/solutions/en/data/1-15NRJ/index.html On Jan 1, 8:17=A0pm, "zhang " <xiao...@gmail.com> wrote: > Hi guys > > I want to solve this kind of equation: > > a*x + b...

Dear sir Can NDSolve in Mathematica solves the nonlinear reaction diffusion equation in two dimensions (Tt-Uxx-Uyy=f(U) with Drichlit B.C.). I ask u kindly to send me the mathematica program solves the transient heat equation in two dimension or the heat diffusion equation if u already have it. Thanks in advance for help and cooperation regards khaled sayed Khaled Sayed Mahmoud Ibrahim Department of MathematicsFaculty of ScienceHelwan University Helwan, Cairo, EgyptTel.: (+20)18-25-35-272 Fax: (+20)-2-25588-586k_s_mahmoud@hotmail.com ...

hello I am trying to solve diffusion equation in dC(x,t)/dt=D*{d^2C(x,t)/dx^2} using matlab but i can't fine any solution for this so pleas help me as soon as possible. "mustakahmed Badi" wrote in message <m8e6u1$4rr$1@newscl01ah.mathworks.com>... > hello > > I am trying to solve diffusion equation in dC(x,t)/dt=D*{d^2C(x,t)/dx^2} using matlab but i can't fine any solution for this so pleas help me as soon as possible. help pdepe Best wishes Torsten. ...

Resources last updated: 1/26/2016 12:09:21 PM