No convergence of cfdemSover

Hi, all

I just simulate a paked bed, 7000 particles were paked in a cylinder. But I did not get a convergency solution, especially the pressure. The Figure of residual is in attachment. The FvSolution are presented. someone can help me?

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.6 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
p
{
solver GAMG;
tolerance 1e-07;
relTol 0.1;
smoother GaussSeidel;
nPreSweeps 0;
nPostSweeps 2;
cacheAgglomeration on;
agglomerator faceAreaPair;
nCellsInCoarsestLevel 10;
mergeLevels 1;
}

pFinal
{
$p;
tolerance 1e-6;
relTol 0;
}

U
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-05;
relTol 0.1;
}

UFinal
{
$U
}

"(k|epsilon)"
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
}
"(k|epsilon)Final"
{
$epsilon;
relTol 0;
}

R
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0;
}

nuTilda
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0;
}

}

PISO
{
nCorrectors 2;
nNonOrthogonalCorrectors 0;
}