Hi @giovastabile and contributors:
I'm sorry to bother you. I've been experimenting with the 21unsteadyNSTurb_RBF tutorial and meeted some issues. I have tried to solve some problems, but there is a problem that still cannot be solved, so I would like to ask you for help:

Before the problem, I was using version OF2106.

1. Boundary condition error of nut.
   Initial boundary conditions of nut as follows:

sides
{
    type            zeroGradient;
}
cylinder1
{
    type            zeroGradient;
}

Using this Boundary will meet a foam erro:

--> FOAM FATAL ERROR: (openfoam-2106)
Attempt to cast type zeroGradient to type nutWallFunction at index 4

So I changed the boundary condition of nut :

sides
{
    type            nutkWallFunction;
    Cmu             0.09;
    kappa           0.41;
    E                  9.8;
    value           uniform 1e-5;
}
cylinder1
{
    type            nutkWallFunction;
    Cmu             0.09;
    kappa           0.41;
    E                  9.8;
    value           uniform 1e-5;
}

2. After this change, I meet a same problem like Problem Running Unsteady NS Turbulent RBF #401

21unsteadyNSTurb_RBF: /home/dyfluid/ITHACA-FV/src/thirdparty/Eigen/Eigen/src/Core/Block.h:120: Eigen::Block<XprType, BlockRows, BlockCols, InnerPanel>::Block(XprType&, Eigen::Index) [with XprType = Eigen::Matrix<double, -1, -1>; int BlockRows = 1; int BlockCols = -1; bool InnerPanel = false; Eigen::Index = long int]: Assertion `(i>=0) && ( ((BlockRows==1) && (BlockCols==XprType::ColsAtCompileTime) && i<xpr.rows()) ||((BlockRows==XprType::RowsAtCompileTime) && (BlockCols==1) && i<xpr.cols()))' failed.

I took a good look at #401 and commented out the following code in "ITHACA_FOMPROBLEMS/UnsteadyNSTurb/UnsteadyNSTurb.C:":

nut = turbulence->nut());

But the change didn't work.

Is there any suggestion or insights you might have?

Thanks!