diff --git a/src/Numos.CoreSim/Solvers/AdvectionSolver.cs b/src/Numos.CoreSim/Solvers/AdvectionSolver.cs
index 2ee5003..b687ecd 100644
--- a/src/Numos.CoreSim/Solvers/AdvectionSolver.cs
+++ b/src/Numos.CoreSim/Solvers/AdvectionSolver.cs
@@ -1072,8 +1072,8 @@ private static bool IsBoundary(AtmosChunk chunk, Int3 position)
         return position.X == 0 ||
                position.X == chunk.Width - 1 ||
                position.Y == 0 ||
-               position.Y == chunk.Height - 1 ||
-               chunk.Depth > 1 && (position.Z == 0 || position.Z == chunk.Depth - 1);
+               position.Z == 0 ||
+               position.Z == chunk.Depth - 1;
     }
 
     /// <summary>
diff --git a/src/Numos.CoreSim/Solvers/BoundaryFlowSolver.cs b/src/Numos.CoreSim/Solvers/BoundaryFlowSolver.cs
index 43ecbb6..bb70f46 100644
--- a/src/Numos.CoreSim/Solvers/BoundaryFlowSolver.cs
+++ b/src/Numos.CoreSim/Solvers/BoundaryFlowSolver.cs
@@ -124,9 +124,6 @@ private static void ProcessBoundaryFlow(
         TryFlowToNeighbor(context, sourceChunk, sourcePosition, localPosition + Int3.PosX, Int3.PosX, injectionBuffer);
         TryFlowToNeighbor(context, sourceChunk, sourcePosition, localPosition + Int3.NegY, Int3.NegY, injectionBuffer);
         TryFlowToNeighbor(context, sourceChunk, sourcePosition, localPosition + Int3.PosY, Int3.PosY, injectionBuffer);
-        if (sourceChunk.Depth <= 1)
-            return;
-
         TryFlowToNeighbor(context, sourceChunk, sourcePosition, localPosition + Int3.NegZ, Int3.NegZ, injectionBuffer);
         TryFlowToNeighbor(context, sourceChunk, sourcePosition, localPosition + Int3.PosZ, Int3.PosZ, injectionBuffer);
     }
diff --git a/src/Numos.CoreSim/Solvers/DefaultAtmosSolvers.cs b/src/Numos.CoreSim/Solvers/DefaultAtmosSolvers.cs
index 2ffaec9..219f1b8 100644
--- a/src/Numos.CoreSim/Solvers/DefaultAtmosSolvers.cs
+++ b/src/Numos.CoreSim/Solvers/DefaultAtmosSolvers.cs
@@ -49,7 +49,7 @@ private static int GetBoundaryVoxelCount(int width, int height, int depth)
         int voxelCount = checked(width * height * depth);
         int interiorWidth = Math.Max(0, width - 2);
         int interiorHeight = Math.Max(0, height - 2);
-        int interiorDepth = depth > 1 ? Math.Max(0, depth - 2) : 1;
+        int interiorDepth = Math.Max(0, depth - 2);
         int interiorVoxelCount = checked(interiorWidth * interiorHeight * interiorDepth);
         return voxelCount - interiorVoxelCount;
     }