if dX_Low ==0, set it equal to dX_High

Author: ptrbortolotti

openfast_toolbox/fastfarm/FASTFarmCaseCreation.py

@@ -2457,6 +2457,8 @@ def _getBoxesParamsForFF(self, lowbts, highbts, dt_low_desired, D, HubHt, xWT, y
         # ----- Low
         dT_Low = getMultipleOf(dt_low_desired, multipleof=dT_High)
         dX_Low = getMultipleOf(meanU_Low*dT_Low, multipleof=dX_High)
+        if dX_Low == 0.:
+            dX_Low = dX_High
         dY_Low = lowbts.y[1] - lowbts.y[0]
         dZ_Low = lowbts.z[1] - lowbts.z[0]