Struct MacGrid 

pub struct MacGrid {
    pub nx: usize,
    pub ny: usize,
    pub dx: f64,
    pub cells: Vec<MacCell>,
}

A 2-D Marker-and-Cell (MAC) grid for incompressible fluid simulation.

The grid is stored in row-major order: cells[j * nx + i] is column i, row j.

Fields

nx: usize

Number of cells in the x direction.

ny: usize

Number of cells in the y direction.

dx: f64

Cell width / height (uniform, square cells, m).

cells: Vec<MacCell>

Flat cell storage (ny * nx entries).

Implementations

impl MacGrid

pub fn new(nx: usize, ny: usize, dx: f64) -> Self

Create a new MAC grid filled with default (fluid) cells.

pub fn cell(&self, i: usize, j: usize) -> &MacCell

Return a shared reference to the cell at column i, row j.

pub fn cell_mut(&mut self, i: usize, j: usize) -> &mut MacCell

Return a mutable reference to the cell at column i, row j.

pub fn divergence(&self, i: usize, j: usize) -> f64

Discrete divergence of velocity at cell (i, j).

Uses the MAC staggered layout: east-face minus west-face for u_x, north-face minus south-face for u_y. Boundary faces are treated as zero (no-flux).

pub fn pressure_solve_jacobi(&mut self, n_iter: usize)

Jacobi iteration pressure solve for the Poisson equation ∇²p = ρ/Δt · ∇·u.

n_iter sweeps are performed. Boundary cells keep zero pressure.

pub fn advect_velocity(&mut self, dt: f64)

Semi-Lagrangian advection of velocity components.

Each face velocity is traced back by dt seconds and the value at the departure point is interpolated bilinearly.

pub fn project(&mut self, dt: f64)

Pressure-projection step: subtract the pressure gradient from velocity.

dt is the time-step; rho is fluid density (kg/m³).

Trait Implementations

impl Clone for MacGrid

fn clone(&self) -> MacGrid

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MacGrid

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.