[en] The grid dependency, such as coordinate system and spatial resolutions, are examined in a large-eddy simulation (LES) for buoyant flows generated by a horizontal upward-facing round plate heated at a high temperature. Two coordinate systems and three grid resolutions are used, i.e., one is the Cartesian and the other is a cylindrical coordinate system with coarse, fire, and very-fine resolutions. The higher-order moments of velocity and temperature fluctuations clearly show the grid dependency, whereas all coordinate systems give the similar profiles of 1st - and 2nd-order turbulence statistics. This implies that the LES for examining the temporal- and spatial-structures of the boundary layer and plume flows must require the well resolved grids for near-wall regions and also the coordinate system to grasp the developing process with large-scale fluid motions. (author)