TY - EJOU AU - Gibou, Frédéric AU - Min, Chohong AU - Ceniceros, Hector D. TI - Non-Graded Adaptive Grid Approaches to the Incompressible Navier-Stokes Equations T2 - Fluid Dynamics \& Materials Processing PY - 2007 VL - 3 IS - 1 SN - 1555-2578 AB - We describe two finite difference schemes for simulating incompressible flows on nonuniform meshes using quadtree/octree data structures. The first one uses a cell-centered Poisson solver that yields first-order accurate solutions, while producing symmetric linear systems. The second uses a node-based Poisson solver that produces second-order accurate solutions and second-order accurate gradients, while producing nonsymmetric linear systems as the basis for a second-order accurate Navier-Stokes solver. The grids considered can be non-graded, i.e. the difference of level between two adjacent cells can be arbitrary. In both cases semi-Lagrangian methods are used to update the intermediate fluid velocity in a standard projection framework. Numerical results are presented in two and three spatial dimensions. KW - DO - 10.3970/fdmp.2007.003.037