Abstract:In this paper an implicit preconditioned gridless method is developed for solving Euler equations at low Mach numbers. The conservative preconditioned system is obtained by multiplying a preconditioning matrix of the type of Weiss and Smith to the time derivative of the three dimensional Euler equations, which are discretized under the clouds of points distributed in the computational domain by using a gridless technique. The implementations of the preconditioned gridless methods are mainly based on the frame of the traditional gridless method without preconditioning, therefore the modifications corresponding to the affect terms of preconditioning such as spectral radius, artificial dissipation and farfield boundary condition are first addressed in the paper. The lower-upper symmetric Gauss-Seidel(LU-SGS) algorithm is then introduced by reordering and splitting the cloud of points to form the implicit preconditioned gridless method. The proposed method is validated by simulating flows over typical airfoils and wing. The numerical results show that the convergence of the method presented is much faster than its explicit counterpart. It is also demonstrated that the presented methods still functions for compressible transonic flow simulations and additionally, for nearly incompressible flow simulations at low Mach numbers as well. Finally, the flows over wing-body configuration at low Mach number are simulated, which intends to show the potential ability of the method presented for coping with flows over practical aerodynamic geometries.