diff --git a/amr-wind/ocean_waves/relaxation_zones/linear_waves_ops.H b/amr-wind/ocean_waves/relaxation_zones/linear_waves_ops.H
index f780192e7a..9c87f7ff8f 100644
--- a/amr-wind/ocean_waves/relaxation_zones/linear_waves_ops.H
+++ b/amr-wind/ocean_waves/relaxation_zones/linear_waves_ops.H
@@ -73,7 +73,9 @@ struct InitDataOp<LinearWaves>
 
                         phi(i, j, k) = eta - zc;
 
-                        if (phi(i, j, k) + 0.5 * dx[2] >= 0) {
+                        const amrex::Real cell_length_2D =
+                            std::sqrt(std::pow(dx[0], 2) + std::pow(dx[2], 2));
+                        if (phi(i, j, k) + cell_length_2D >= 0) {
                             vel(i, j, k, 0) =
                                 omega * wave_height / 2.0 *
                                 std::cosh(
@@ -95,7 +97,9 @@ struct InitDataOp<LinearWaves>
                     gbx3, [=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept {
                         const amrex::Real z = problo[2] + (k + 0.5) * dx[2];
                         phi(i, j, k) = zsl - z;
-                        if (phi(i, j, k) + 0.5 * dx[2] >= 0) {
+                        const amrex::Real cell_length_2D =
+                            std::sqrt(std::pow(dx[0], 2) + std::pow(dx[2], 2));
+                        if (phi(i, j, k) + cell_length_2D >= 0) {
                             vel(i, j, k, 0) = 0.0;
                             vel(i, j, k, 1) = 0.0;
                             vel(i, j, k, 2) = 0.0;
@@ -157,7 +161,9 @@ struct UpdateRelaxZonesOp<LinearWaves>
 
                         phi(i, j, k) = eta - zc;
 
-                        if (phi(i, j, k) + 0.5 * dx[2] >= 0) {
+                        const amrex::Real cell_length_2D =
+                            std::sqrt(std::pow(dx[0], 2) + std::pow(dx[2], 2));
+                        if (phi(i, j, k) + cell_length_2D >= 0) {
                             vel(i, j, k, 0) =
                                 omega * wave_height / 2.0 *
                                 std::cosh(
diff --git a/amr-wind/ocean_waves/relaxation_zones/stokes_waves_ops.H b/amr-wind/ocean_waves/relaxation_zones/stokes_waves_ops.H
index 7d8f4a3a86..8a2b68ad25 100644
--- a/amr-wind/ocean_waves/relaxation_zones/stokes_waves_ops.H
+++ b/amr-wind/ocean_waves/relaxation_zones/stokes_waves_ops.H
@@ -109,7 +109,9 @@ struct InitDataOp<StokesWaves>
                             zero_sea_level, g, x, z, 0.0, eta, u_w, v_w, w_w);
 
                         phi(i, j, k) = eta - z;
-                        if (phi(i, j, k) + 0.5 * dx[2] >= 0) {
+                        const amrex::Real cell_length_2D =
+                            std::sqrt(std::pow(dx[0], 2) + std::pow(dx[2], 2));
+                        if (phi(i, j, k) + cell_length_2D >= 0) {
                             vel(i, j, k, 0) = u_w;
                             vel(i, j, k, 1) = v_w;
                             vel(i, j, k, 2) = w_w;
@@ -121,7 +123,9 @@ struct InitDataOp<StokesWaves>
                     gbx3, [=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept {
                         const amrex::Real z = problo[2] + (k + 0.5) * dx[2];
                         phi(i, j, k) = zero_sea_level - z;
-                        if (phi(i, j, k) + 0.5 * dx[2] >= 0) {
+                        const amrex::Real cell_length_2D =
+                            std::sqrt(std::pow(dx[0], 2) + std::pow(dx[2], 2));
+                        if (phi(i, j, k) + cell_length_2D >= 0) {
                             vel(i, j, k, 0) = 0.0;
                             vel(i, j, k, 1) = 0.0;
                             vel(i, j, k, 2) = 0.0;
@@ -178,7 +182,10 @@ struct UpdateRelaxZonesOp<StokesWaves>
                             zero_sea_level, g, x, z, time, eta, u_w, v_w, w_w);
 
                         phi(i, j, k) = eta - z;
-                        if (phi(i, j, k) + 0.5 * dx[2] >= 0) {
+                        const amrex::Real cell_length_2D =
+                            std::sqrt(std::pow(dx[0], 2) + std::pow(dx[2], 2));
+                        if (phi(i, j, k) + cell_length_2D >= 0) {
+                            // Wave velocity within a cell of interface
                             vel(i, j, k, 0) = u_w;
                             vel(i, j, k, 1) = v_w;
                             vel(i, j, k, 2) = w_w;
diff --git a/amr-wind/ocean_waves/relaxation_zones/waves2amr_ops.H b/amr-wind/ocean_waves/relaxation_zones/waves2amr_ops.H
index 95ae72ed58..d8e86390d6 100644
--- a/amr-wind/ocean_waves/relaxation_zones/waves2amr_ops.H
+++ b/amr-wind/ocean_waves/relaxation_zones/waves2amr_ops.H
@@ -90,7 +90,9 @@ void postprocess_velocity_mfab_liquid(
         amrex::ParallelFor(
             gbx, [=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept {
                 // Set velocity to zero if no liquid present
-                if (phi(i, j, k) + 0.5 * dx[2] < 0.0) {
+                const amrex::Real cell_length_2D =
+                    std::sqrt(std::pow(dx[0], 2) + std::pow(dx[2], 2));
+                if (phi(i, j, k) + cell_length_2D >= 0) {
                     vel(i, j, k, 0) = 0.0;
                     vel(i, j, k, 1) = 0.0;
                     vel(i, j, k, 2) = 0.0;