Body-fitted grid

Such a body-fitted grid is shown on the right side of Figure 2.13. 

Figure 2.13 2-D Cartesian (left) and body-fitted grid (right) defined on a curved pipe.

A face of a rectangular-grid cell overlaps with several faces of body-fitted grid cells. 

A body-fitted grid with approximately 200.000 nodes. Figure 12, is used to represent the secondary reaction zone of the investigated test stove. 

Subdivision or discretization of the flow domain into cells or elements. There are methods, called boundary element methods, in which the surface of the flow domain, rather than the volume, is discretized, but the vast majority of CFD work uses volume discretization. Discretization produces a set of grid lines or cuives which define a mesh and a set of nodes at which the flow variables are to be calculated. The equations of motion are solved approximately on a domain defined by the grid. Curvilinear or body-fitted coordinate system grids may be used to ensure that the discretized domain accurately represents the true problem domain. 

Figure 2.23 Arbitrary interface between a body-fitted and a rectangular grid.

J.F. Thompson, Z.U.A. Warsi, and C.W. Mastin (1974) Automatic numerical generation of body-fitted curvilinear coordinate system for field containing any number of arbitrary two-dimensional bodies. J. Comput. Phys. 15, 299-319. J.F. Thompson, Z.U.A. Warsi, and C.W. Mastin (1985) Numerical Grid Generation. North-Holland, New York. 

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