From 3f04cfc6eebe3c66ef8643a86f74b813bfe9c8f4 Mon Sep 17 00:00:00 2001
From: Surbhi <53841577+surbhidhiman@users.noreply.github.com>
Date: Wed, 19 Nov 2025 22:00:49 -0800
Subject: [PATCH] Added skeleton code for lock exchange implementation

---
 examples/lock_exchange.jl | 63 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 examples/lock_exchange.jl

diff --git a/examples/lock_exchange.jl b/examples/lock_exchange.jl
new file mode 100644
index 0000000000..3bc8031b1f
--- /dev/null
+++ b/examples/lock_exchange.jl
@@ -0,0 +1,63 @@
+using Oceananigans
+using Oceananigans.Units
+using Oceananigans.Grids: MutableVerticalDiscretization
+
+
+# Set resolution of the simulation grid 
+Nx, Nz = 256, 64
+
+# Set grid size 
+L = 8kilometers   # horizontal length
+H = 50meters      # depth  
+
+# Allow for mutable surface height 
+z_disc  = MutableVerticalDiscretization((-50, 0))
+
+# Initialize the grid 
+underlying_grid = RectilinearGrid(
+                    size = (Nx, Nz),
+                    x = (0, L),
+                    z = z_disc,
+                    topology = (Bounded, Flat, Bounded), 
+                    halo = (5, 5)
+)
+
+# Add a slope at the bottom of the grid 
+h_left = -H
+h_right = -25meters
+slope = (h_right - h_left) / L
+bottom(x) = h_left + slope * x
+
+# Use an immersed boundary with grid fitted bottom to describe the sloped bottom of the domain 
+grid = ImmersedBoundaryGrid(underlying_grid, GridFittedBottom(bottom))
+
+# Initialize the model 
+    # Want to use a hydrostatic model 
+    # Tracers act as markers within the fluid to track movement and dispersion
+    # Weighted Essentially Non-Oscillatory (WENO) methods are useful for capturing sharp changes in density
+    # Closures simplify complex systems by approximating the effects of unresolved scales
+    # ZStarCoordinate allows for the top of the grid to move with the free surface
+    # Runge Kutta good for integrating multiple processes 
+
+model = HydrostaticFreeSurfaceModel(; grid,
+    tracers = (:b,),
+    buoyancy = BuoyancyTracer(),
+    momentum_advection = WENO(order=5), 
+    tracer_advection = WENO(order=7), 
+    closure = (VerticalScalarDiffusivity(ν=1e-4), HorizontalScalarDiffusivity(ν=1.0)), 
+    vertical_coordinate = ZStarCoordinate(grid), 
+    free_surface = SplitExplicitFreeSurface(grid; substeps=10), 
+    timestepper = :SplitRungeKutta3 
+)
+
+# Set initial conditions for lock exchange with different densities 
+bᵢ(x, z) = x > 4kilometers ? 0.06 : 0.01
+set!(model, b=bᵢ)
+
+# Set the timesteps 
+Δt = 5minutes
+stop_time = 3days
+simulation = Simulation(model; Δt, stop_time)
+
+# Run simulation
+run!(simulation)
\ No newline at end of file