Can anybody help me to code boundary conditions in MATLAB for Keller Box Method?

Question

Prachi 2023-8-6

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https://ww2.mathworks.cn/matlabcentral/answers/2005302-can-anybody-help-me-to-code-boundary-conditions-in-matlab-for-keller-box-method

评论： vijayakumar 2024-10-30

f^'=1,f=S,θ^'=-r_1 [1+θ],ϕ^'=-r_2 [1+ϕ]               at            η=0
f^'=0,f^''=0,θ=0,ϕ=0                as                η→∞  

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vijayakumar 2024-10-30

how to set MATLAB code for velocity slip and temperature slip boundary condition for kelller box method please help me out

at eta=0, f(eta)=0, f^'(eta)=SF*f^''(eta), theta=1+ST*theta^'(eta)

at eta=infinite, f^'=0, theta=0

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Answer 1

Mrutyunjaya Hiremath 2023-8-6

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在 MATLAB Online 中打开

% Define parameters

r_1 = 0.1;

r_2 = 0.2;

S = 2.0;

% Define the differential equations

% y(1) = f, y(2) = f', y(3) = θ, y(4) = ϕ

ode_system = @(eta, y) [y(2); 1; y(3); y(4)];

% Define the boundary conditions at η = 0

initial_conditions = [S, 1, 0, 0];

% Define the boundary conditions at η → ∞

eta_infinity = 100; % Choose a large value

final_conditions = [0, 0, 0, 0];

% Solve the differential equations

[eta, result] = ode45(ode_system, [0, eta_infinity], initial_conditions);

% Extract the solutions

f = result(:, 1);

f_prime = result(:, 2);

theta = result(:, 3);

phi = result(:, 4);

% Plot the solutions

subplot(2, 2, 1);

plot(eta, f);

xlabel('η');

ylabel('f');

title('f vs. η');

subplot(2, 2, 2);

plot(eta, f_prime);

xlabel('η');

ylabel("f'");

title("f' vs. η");

subplot(2, 2, 3);

plot(eta, theta);

xlabel('η');

ylabel('θ');

title('θ vs. η');

subplot(2, 2, 4);

plot(eta, phi);

xlabel('η');

ylabel('ϕ');

title('ϕ vs. η');

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Torsten 2023-8-7

It should be clear that we won't program this for you.

If you have a boundary value problem as above, you can use the MATLAB tools "bvp4c" or "bvp5c".

If your problem is an assignment, you will have to start programming it in MATLAB or make a google search whether you find a MATLAB code that fits your needs.

Thiripura Sundari 2024-9-27

Good evening Professor, Shall we give matlab bvp4c code in jeffrey fluid thank you.

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Answer 2

Santosh Devi 2024-2-27

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f^''' (η)+ff^'' (η)-(f^' (η))^2+Mf^' (η)-λf(η)=0

■θ^'' (η)+Pr⁡[f(η)θ^' (η)-b/(u_w^2 ) ηθ(η)+Ec(f^'' (η))^2+Q_0 θ(η)]=0

■ϕ^'' (η)+Sc[f(η) ϕ^' (η)-Kϕ(η)]=0

■f(0)=s,f^' (0)=1,θ(0)=1,ϕ(0)=1

■f^' (∞)→0,θ(∞)→0,ϕ(∞)→0

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Santosh Devi 2024-2-27

在 MATLAB Online 中打开

function plot_velocity_vs_eta()
    % Parameters
    lambda = 0.1;
    Pr = 0.72;
    b = 1;
    uw = 1;
    Ec = 0.0001;
    Q0 = 1;
    Sc = 1;
    K = 1;
    s = 1;
    M_values = [0, 0.5, 1];
    % Initialize plot
    figure;
    hold on;
    % Iterate over each Prandtl number
    for i = 1:length(M_values)
        M = M_values(i);
        % Define the system of equations
        equations = @(eta, y) [
            y(2);                                                       % f'(eta) = y(2)
            y(3);                                                       % f''(eta) = y(3)
            -y(1)*y(3) + y(2)^2 - M*y(2) + lambda*y(1);                % theta'(eta) = y(3)
            -Pr * (y(1)*y(4) - b/(uw^2)*eta*y(3) + Ec*y(3)^2 + Q0*y(4)); % theta''(eta)
            y(6);                                                       % phi'(eta) = y(6)
            -Sc * (y(1)*y(6) - K*y(6))                                  % phi''(eta)
        ];
        % Define the boundary conditions function
        bc = @(ya, yb) boundary_conditions(ya, yb, s);
        % Solve the equations
        eta_span = [0, 10];
        initial_conditions = [s; 0; 1; 1; 0; 0]; % Initial guesses for f, f', theta, phi, f'', phi'
        options = odeset('RelTol', 1e-6, 'AbsTol', 1e-9);
        [eta, solution] = ode45(equations, eta_span, initial_conditions, options);
        % Calculate velocity (f'(eta))
        velocity = solution(:, 2);
        % Plot velocity against eta
        plot(eta, velocity, '-', 'LineWidth', 2, 'DisplayName', sprintf('M = %.2f', M));
    end
    % Add labels and legend
    xlabel('\eta');
    ylabel('Velocity (f''(\eta))');
    title('Velocity Profile for Different M Numbers');
    legend('Location', 'best');
    grid on;
    hold off;
end
function res = boundary_conditions(ya, yb, s)
    % Boundary conditions
    res = [ya(1) - s; ya(2); ya(3) - 1; ya(5) - 1; ya(4); ya(6); yb(1) - s; yb(2); yb(3) - 1; yb(5) - 1; yb(4); yb(6)];
end

Thiripura Sundari 2024-10-22

Good afternoon Professor, can please give fourth order jeffrey fluid using keller box method

vijayakumar 2024-10-30

@Santosh Devi above code is which method

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Can anybody help me to code boundary conditions in MATLAB for Keller Box Method?

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Can anybody help me to code boundary conditions in MATLAB for Keller Box Method?

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