[CFD padawan]

Hello Everyone,

Currently, I'm working on exterior ballistics and have developed access to a 6DOF ballistic calculator. To make the calculator operational, various coefficients at different velocities are required. Presently, I'm endeavoring to create a model to determine these coefficients for the 6.5 Creedmoor. This involves considering a MRF along with projectile geometry. The projectile spins at approximately 242,000 rpm.

Now, to the main issue: I'm utilizing snappyHexMesh for mesh generation, but I'm encountering difficulties achieving a smooth surface over the projectile. Please refer to the attached image illustrating the mesh domain cross-section. As I'm relatively new to Computational Fluid Dynamics (CFD), I appreciate your patience.

Any recommendations for sources (books, websites, etc.) or instructions would be highly valued.

Best regards,
D
P.S. snappyMeshDict is below

/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 7
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object snappyHexMeshDict;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

castellatedMesh true;
snap true;
addLayers false;

geometry
{
projectile
{
type triSurfaceMesh;
file "projectile_m.stl";
}
inlet
{
type triSurfaceMesh;
file "inlet_m.stl";
}
outlet
{
type triSurfaceMesh;
file "outlet_m.stl";
}
boundary
{
type triSurfaceMesh;
file "boundary_m.stl";
}

//- Used to define MRF zone and to refine mesh round the impeller
MRF
{
type searchableCylinder;
point1 (.076 0.0 0.0);
point2 (.130 0.0 0.0);
radius .004;
}
}


castellatedMeshControls
{

maxLocalCells 100000;

maxGlobalCells 2000000;

minRefinementCells 0;

nCellsBetweenLevels 2;

maxLoadUnbalance 0.10;

resolveFeatureAngle 1;
planarAngle 1;

features
(
{
file "projectile_m.eMesh";
level 7;
}

{
file "inlet_m.eMesh";
level 0;
}
{
file "outlet_m.eMesh";
level 0;
}
{
file "boundary_m.eMesh";
level 0;
}
);

refinementSurfaces
{
MRF
{
level (1 1);
cellZone cellMRFzone;
faceZone faceMRFzone;
cellZoneInside inside;
}

projectile
{
level (5 6);
}

inlet
{
level (0 0);
}

outlet
{
level (0 0);
}

boundary
{
level (0 0);
}
}

refinementRegions
{
MRF
{
mode inside;
levels ((1E15 4));
}

}

locationInMesh (0.080 0.0 0.0); // Inside point

allowFreeStandingZoneFaces true;
}

// Settings for the snapping.
snapControls
{

nSmoothPatch 3;

tolerance 1.0;

nSolveIter 300;

nRelaxIter 50;

nFeatureSnapIter 10;

implicitFeatureSnap false;

explicitFeatureSnap true;

multiRegionFeatureSnap false;
}

// Settings for the layer addition.
addLayersControls
{

relativeSizes true;

layers
{
}

}

meshQualityControls
{
#include "meshQualityDict"

// Advanced

//- Number of error distribution iterations
nSmoothScale 4;
//- Amount to scale back displacement at error points
errorReduction 0.75;
}

writeFlags
(
);

mergeTolerance 1E-6;


// ************************************************** *********************** //