Function swe

examples/pde/swe.cpp:17–102

}

static void swe(bool console) {
    // Grid length, number and spacing
    const unsigned Lx = 1600, nx = Lx + 1;
    const unsigned Ly = 1600, ny = Ly + 1;
    const float dx = Lx / (nx - 1);
    const float dy = Ly / (ny - 1);

    array ZERO = constant(0, nx, ny);
    array um = ZERO, vm = ZERO;
    unsigned io = (unsigned)floor(Lx / 6.0f), jo = (unsigned)floor(Ly / 6.0f),
             k = 15;
    array x    = tile(range(nx), 1, ny);
    array y    = tile(range(dim4(1, ny), 1), nx, 1);

    // initial condition
    array etam =
        0.01f * exp((-((x - io) * (x - io) + (y - jo) * (y - jo))) / (k * k));
    float m_eta = max<float>(etam);
    array eta   = etam;
    float dt    = 0.5;

    // conv kernels
    float h_diff_kernel[] = {9.81f * (dt / dx), 0, -9.81f * (dt / dx)};
    float h_lap_kernel[]  = {0, 1, 0, 1, -4, 1, 0, 1, 0};

    array h_diff_kernel_arr(3, h_diff_kernel);
    array h_lap_kernel_arr(3, 3, h_lap_kernel);

    if (!console) {
        win = new Window(1536, 768, "Shallow Water Equations");
        win->grid(2, 2);
    }

    unsigned iter            = 0;
    unsigned random_interval = 30;

    while (!win->close()) {
        if (iter > 2000) {
            // Initial condition
            etam  = 0.01f * exp((-((x - io) * (x - io) + (y - jo) * (y - jo))) /
                                (k * k));
            m_eta = max<float>(etam);
            eta   = etam;
            iter  = 0;
        }

        // raindrops
        if (iter % 100 == 0 || iter % 130 == 0 || iter % random_interval == 0) {
            unsigned io     = (unsigned)floor(rand() % Lx),
                     jo     = (unsigned)floor(rand() % Ly);
            random_interval = rand() % 200 + 1;
            eta += 0.01f * exp((-((x - io) * (x - io) + (y - jo) * (y - jo))) /
                               (k * k));
        }

        // compute
        array up   = um + convolve(eta, h_diff_kernel_arr);
        array vp   = um + convolve(eta, h_diff_kernel_arr.T());