Curvilinear grid and velocity at rho-points problem

[kenlagamayo]

Hi Everyone,

For a brief introduction.
I was creating my curvilinear grid using the RGFGRID of Delft3D to delineate the curvature of the estuary I am interested in.
The river has a dam and only half of the channel is opened to allow dam discharge during ebb tide. Also, the area is macrotidal so, during ebb tides, the tidal flats are very prominent. Because of these, I find it hard to create a working grid.
I tried several times but most of them were not working.

I currently have a working grid but I am afraid that there may still be problems.
I orthogonalize the grid except for one section (red dotted areas) since I am after the direction of the water flow that follows the channel during ebb tide (lines inside the river).

I didn't use the nesting method but instead, I gradually decreased the size of the cells in certain regions for higher resolution using the smoothing function of the software. My pm and pn look like these. I am not sure if there will be problems because of this.

My rx0 and rx1 are also very high.

rx0.PNG (3.3 KiB) Viewed 3574 times

Despite these preconditions, I run the model coupled with SWAN for 14 months. It finished. However, when I looked at the u_eastward and v_northward, there are weird patches within the estuary. There is a distinct "separation" (red rectangle) between the upper and lower section. Also, there are weird regions (red circles) that create a separate domain. Is it because of my orthogonality?

These features only appear in u_eastward and v_northward. I don't see them in zeta, salinity, u, and v.
So I am not sure which part is wrong. Can anyone guide me on this?

Thank you very much for your help.

[jcwarner]

what does the grid angle look like?
also, when you make those pcolor plots, are they
pcolorjw(lon_rho,lat_rho,angle)
and use
pcolorjw(lon_u,lat_u,ubar)
etc

You said the u and v are ok, but the u_east and v_north are not? so that might be an angle issue.

[kenlagamayo]

Thank you! I checked the angle, and it matches the shape of the patches.