I'm trying to solve numerically a 2d/3d reaction-diffusion equation using NDSolve. The system can be solved for one spatial dimension (+ time dimension), but it does not converge for two spatial dimensions (x,y,t). Actually, I'm trying to use polar coordinates (r, phi, t), because the problem has a point source. I'm using NDsolve with the following method: Method -> {"MethodOfLines", "SpatialDiscretization" -> {"TensorProductGrid", "Coordinates" -> myGrid} which fails. Can you recommend a better method to solve the problem in 2D (and eventually in 3D) ? Kind regards, Alois

0 |

1/4/2011 9:22:51 AM

On Tue, 4 Jan 2011, Alois wrote: > I'm trying to solve numerically a 2d/3d reaction-diffusion equation > using NDSolve. The system can be solved for one spatial dimension (+ > time dimension), but it does not converge for two spatial dimensions > (x,y,t). Actually, I'm trying to use polar coordinates (r, phi, t), > because the problem has a point source. > > I'm using NDsolve with the following method: > Method -> {"MethodOfLines", "SpatialDiscretization" -> > {"TensorProductGrid", "Coordinates" -> myGrid} > > which fails. Can you recommend a better method to solve the problem in > 2D (and eventually in 3D) ? > > Kind regards, > Alois > > > > Alois, you find an example of one way to do it here http://library.wolfram.com/infocenter/Conferences/7549/ Hope this helps, Oliver

0 |

1/6/2011 7:06:54 AM

On Tue, 4 Jan 2011, Alois wrote: > I'm trying to solve numerically a 2d/3d reaction-diffusion equation > using NDSolve. The system can be solved for one spatial dimension (+ > time dimension), but it does not converge for two spatial dimensions > (x,y,t). Actually, I'm trying to use polar coordinates (r, phi, t), > because the problem has a point source. > > I'm using NDsolve with the following method: > Method -> {"MethodOfLines", "SpatialDiscretization" -> > {"TensorProductGrid", "Coordinates" -> myGrid} > > which fails. Can you recommend a better method to solve the problem in > 2D (and eventually in 3D) ? > > Kind regards, > Alois > > > > Alois, things like eqn = \[Rho]*cp*D[u[t, x, y], t] - \[Lambda]* D[u[t, x, y], x, x] + -\[Lambda]*D[u[t, x, y], y, y] == f + r*u[t, x, y]*If[x == p1X, y == p1Y, 1, 0] NDSolve[Join[{eqn}, bc, ic], u, {t, 0, tEnd}, {x, 0, xEnd}, {y, 0, yEnd}, Method -> {"MethodOfLines", "SpatialDiscretization" -> {"TensorProductGrid", MaxPoints -> {35, 35}, MinPoints -> {35, 35} }} ]; work in principal. Now, the exact details depend on the equation parameters. Note that the Max and Min points need to be chosen such that the tensor grid generates a point {p1X,p1Y}. Hth, Oliver

0 |

1/8/2011 8:39:19 AM

hiya, is there anything for matlab that will solve a 2D/3D reaction- diffusion problem? I know of pdepe that does 1D, and pdetoolbox that does 2D, but otherwise, would I have to write my own code? thanks! On 2/14/2011 6:44 PM, shawn wrote: > hiya, > > is there anything for matlab that will solve a 2D/3D reaction- > diffusion problem? I know of pdepe that does 1D, and pdetoolbox that > does 2D, but otherwise, would I have to write my own code? > > thanks! I just looked at pdetool, and it does not look it can do 2D diffusion-reaction pde. What are specs of your proble...

Hiya, For my phd thesis, I wrote a custom unstructured finite element (tri / tet) 2D/3D reaction-diffusion solver in matlab. It uses an adams- bashforth / trapezoidal predictor-corrector time integrator with a customised GMRES linear solver (which itself uses matlab's '\' operator), with adaptive time-stepping based on the Gresho and Sani depiction in their CFD books. Hence, this thing handles multiple space and time scales - which I needed for the computational cell biology modeling I performed. Note, there's no Newton solver in it...yet? Anyway, I'm curio...

Hi everyone, I want to numerically solve the following nonlinear two dimensional reaction-diffusion equations by discretising the spatial derivatives using finite difference so that I end up with a set of odes that can be solved using an ode solver -- method of lines. I have had a go at coding the problem in Matlab but got unrealistic/unexpected results. Can someone please have a look at my code and shed some light? I would appreciate any assistance as I am still learning my way around Matlab. Many thanks. The three equations read: du_1/dt=d^2u_1/dx^2 + d^2u_1/dy^2 + u_1u_2-u_1+u_2u_3; ...

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 ...

I need to solve diffusion problem in 3 D with an arbitrary diffusion tensor. Could someone please suggest me if there is any such programme already written or exiting in matlab? ...

Hello all, I'm trying to find a nice and neat way to numerically solve the convective diffusion equation da/dt = D (d^2/dx^2 + d^2/dy^2) a - v da/dx where a is the concentration of my solute, D is the diffusion constant, and v is the surrounding fluid velocity in the x direction. I thought that there was a small chance that maybe someone else here has attempted something similar. Is it even possible to solve this equation? As always, any suggestions would be much appreciated. Cheers, Dan dantimatter wrote: > Hello all, > > I'm trying to find a ni...

Hello all, I'm trying to find a nice and neat way to numerically solve the convective diffusion equation da/dt = D (d^2/dx^2 + d^2/dy^2) a - v da/dx where a is the concentration of my solute, D is the diffusion constant, and v is the surrounding fluid velocity in the x direction. I thought that there was a small chance that maybe someone else here has attempted something similar. Is it even possible to solve this equation? As always, any suggestions would be much appreciated. Cheers, Dan dantimatter <dantimatter@gmail.com> wrote in message <1186153073.038814.223160@d30g20...

Hi @ all, I=B4ve a mix of 3D and 2D files in one folder (about 4000 files). I want to batch convert all 3D files to 2D und leave the 2D files 2D. Is there a possibility to prevent that cnvdgn converts the 2D files into 3D, and just convert the 3D Files into 2D. Thanks in advance brg Andreas run the files through EDG to find out which are 3D and then move the 2D out of the folder ...

I'm trying to consistently use Palatino fonts in my thesis. That includes all numerals. In the main body of text, writing '2' returns a '2' in the Palatino font once complied, but in math mode the '2' is in Times Roman font I think. I've tried using the packages (stabbing in the dark basically). mathpple mathpazo palatinomath palatino palatcm with no luck. Any ideas? Thanks. Chrisr <chrisr@es.co.nz> writes: > mathpple > mathpazo > palatinomath > palatino > palatcm The correct way to use Palatino is mathpazo.sty (see FAQ, psnfss...

1. 2D -> 3D a = zeros(20,30); How to create a 1X20X30 matrix b from a? 2. 3D -> 2D b = zeros(1,20,30); How to create a 20X30 matrix a from b? Any reply will be highly appreciated, :) In article <g29s1q$a2l$1@fred.mathworks.com>, Tao <tw@ualberta.ca> wrote: >1. 2D -> 3D >a = zeros(20,30); >How to create a 1X20X30 matrix b from a? b = permute(a, [3,1,2] ); Or b = reshape(a, [1, size(a)]); >2. 3D -> 2D >b = zeros(1,20,30); >How to create a 20X30 matrix a from b? a = permute(b, [2, 3, 1]); Or a = reshape(b, size(b,2), []); Or a = squeeze(b);...

Hi all, Does anyone know if Mathematica can numerically solve a second order differential equation? Blake Jackson wrote: > Hi all, > > Does anyone know if Mathematica can numerically solve a second order differential equation? > Sure it can. Search the documentation for *NDSolve* [1]. For example (adapted from [2], which is a nice and short introduction to solving ODEs with Mathematica), In[1]:= sol = NDSolve[ {Derivative[2][x][t] + gamma*Derivative[1][x][t] + x[t]^3 == A*Cos[t], x[0] == 0.6, Derivative[1][x][0] == 1.25} /. {gamm...

is it possible to solve nonlinear integral equations numerically with mathematica? i'm trying to solve the following integral equation for the function p[x]: (1 + x^2/5)^(-5) Exp[ArcTan[x]] == p[x] Integrate[p[s] Exp[.5 x s], {s, -Infinity, Infinity}] note this integral equation is nonlinear, ie. not of fredholm or volterra type, due to multiplicative p[x] in front of the integral. i've looked around the documentation for dsolve, ndsolve, ..., but i couln't find any mention of integral equations in the mathematica documentation. searching this lis...

hi everybody, I'd like to know which is best way to solve this kind of equations with HP-50G http://www.wolframalpha.com/input/?i=%28x-senx%29^5-x^2%288192%2F0.7^8%29*%280.4706*0.015%2F%280.004^0.5%29%29^3%3D0 I've stored this equation in the HP but when I try to solve it using "solve equation" a lot of times I'm just getting the first solution, which is 0, as shown in the WolframAlpha graph. How can I be 100% sure that I'll get all the zeros when solving? Which method would you advise? Thank you!!...

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...

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...

http://postimage.org/image/jr35rwdel/ the image above represents spacing rules for engineer stuff. if you look at it you will see the spacing can be summarized as: 1. 7 foot radius circle drawn around the center point of the rectangle. This never changes no matter what the dimensions of the rectangle. So we can ignore this. 2. On the south side of the rectangle, starting at the left and right corners, a 30 degree line is drawn (making a triangle ABC). Once the line reaches the 7 foot radius circle, it only goes 13 foot past it and then curves like a partial circle, keeping 20 fe...

Hello, Can someone help me with an issue about digits and vpa command? The limit of digits in matlab is only 50? For example, I've done the following test: >> digits Digits = 100 >> vpa((1+sqrt(5))/2,100) ans = 1.618033988749894902525738871190696954727172851562500000000000000000000000000000000000000000000000000 (note the 0's) Now, using Mathematica i've able to get it: In[1]:= N[(1+Sqrt[5])/2,100] Out[1]= 1.618033988749894848204586834365638117720309179805762862135448622705260462818902449707207204189391137 Question 1) : How can I get the same answer in Matlab a...

This is really meant as the latest in a series I posted over irregular inte= rvals since last summer, in which I'm going to try and explain some of the = tricks used and call out some of the *real* issues that I'd like to tackle = (like reverse "signal demasking" and reverse "layering") These are the demos where some of the tricks are shown off. Bear in mind th= at everything comes from single photos -- no triangulation, no built-in 3D = models, etc. Lighting, coloring, texture, etc. are also inferred from the p= hotos, not built-in or hard-coded. [0] 2D...

I really like the 2D graphics editing tool. It allows me to add annotation to plots when it is too hard to code these directly. I had a need now to the same but on a 3D plot. It seems the tool only works on 2D (it says on it 2D :) So, I was wondering if one know of a way to edit (add annotation) to a 3D plot? If not, I hope WRI would add such a support in 6.1 thanks, Nasser Nasser Abbasi wrote: > I really like the 2D graphics editing tool. It allows me to add annotation > to plots when it is too hard to code these directly. > > I had a need now to the...

I am trying to find local maxima of an objective function by solving the FOCs of a function of 4 control variables (pL,pH,phiL,phiH) and 3 parameters (c, pDBS,phiDBS). The objective function is f[pL_,phiL_,pH_,phiH_,pDBS_,phiDBS_,c_] = \ (pL-0.5c*phiL^2)*((pH-pL)/(phiH-phiL) - pL/phiL) + \ (pH-0.5c*phiH^2)*((pDBS-pH)/(phiDBS-phiH) - (pH-pL)/(phiH-phiL)) I find the FOCs by differentiating with respect to each of the 4 control variables, and then I solve the system using Solve[] (see details below) For certain values of the parameters (c, pDBS, phiDBS), the Solve[] routine works f...

Start simple and add one thing at a time evaluating the results at each step. Refer to the online documentation often until you are much more experienced--I still use the documentation often. Bob Hanlon On Fri, Apr 27, 2012 at 6:50 AM, luke wallace <lukewallace1990@gmail.com> wrote: > Holy cow. I can't believe that is even possible from just typing code. > It looks like an alien language to me how can I ever hope to know what > I'm doing and write that stuff myself? Are you using some kind of > graphical interface to arrive at that code or something, o...

Hi, This is my first message to the math group, and I am really new to Mathematica as well. I would really appreciate if someone could help me with this, as I did not find much help in the documentation or the forum regarding my problem. Here are the details: I have these three diffusion equations that I need to solve using the NDSolve function. solution = {r, a, s} /. First[NDSolve[{D[r[x,t], t] == -r[x,t] + �[(s[x,t] - a[x,t] + g[x,t] - Subscript[c, r])/Subscript[b, r]], Subscript[�,a]*D[a[x,t],t] == D[a[x,t], x, x] - a[x,t] + �*�[(s[x, t] - a[x, t] + g[x,t] - Subscrip...

Use Manipulate. Here is a partial example : Manipulate[ Module[ {tan, ll, lr, ur, r, pt, t}, tan = Tan[30 Degree]; ll = {-w/2, -d/2}; lr = {w/2, -d/2}; ur = {w/2, d/2}; r = Sqrt[(20 + d/2)^2 + (w/2)^2]; pt = {x, y} /. FindRoot[ {tan == (x - w/2)/(y - d/2), x^2 + y^2 == r^2}, {x, 12}, {y, 20}]; t = ArcTan @@ Reverse[pt]; Graphics[ {Thin, Circle[{0, 0}, 7], Line[{{-7, -4}, {-7, 4}}], Circle[{0, 0}, r, -90 Degree + {-t, t}], {AbsoluteDashing[{6, 6, 72, 6}], Line[{{0, 9}, {0, -22 - d/2}}]}, {White, EdgeForm[Thick], Re...

i want to write Matlab program of gaussian beam (2D or 3D) using helmholtz equation.... if anyone could give the full program, that will help me to do my project work...... thank you :) "Debashis Roy" <deba4u@ymail.com> wrote in message <lhv04i$6sf$1@newscl01ah.mathworks.com>... > i want to write Matlab program of gaussian beam (2D or 3D) using helmholtz equation.... if anyone could give the full program, that will help me to do my project work...... > > thank you :) If anyone could give the full program, they WILL do your project work, not just h...

Text is available under the Creative Commons Attribution-ShareAlike License ;additional terms may apply. By using this site, you agree to the ...

Get Equilibrium - Can You Strike A Numerical Balance? on the App Store. See screenshots and ratings, and read customer reviews.

This is a numerical simulation of the orientation of Nix as seen from the center of the Pluto system. It has been sped up so that one orbit of ...

THERE will be a Chris Waller-like feel at the Gold Coast races on Sunday when local trainer Gillian Heinrich saddles up four of the 10 runners ...

... simply tap an item for more information, such as manufacturing process and any common side effects, typically stated in layman’s terms. Numerical: ...

Holen Sie sich „Numerical: Calculator Without Equal“ im App Store. Sehen Sie sich Screenshots, Bewertungen und Kundenrezensionen dazu an.

... deals on well-designed apps, however, we'll also bring them to your attention individually — and such is the case with Andrew J Clark's " Numerical ...

... response to incoming data on the economy . Many participants thought that more-effective forward guidance could be provided by specifying numerical ...

Quentin Tarantino is a filmmaker who is known for making particular kinds of films, with adrenaline and testosterone always on full display, ...

AFP Divided Fed considers numerical triggers for rates policy CNBC.com WASHINGTON (Reuters) - The US Federal Reserve may adopt numerical thresholds ...

Resources last updated: 2/22/2016 2:37:40 AM