2D Modelling across large areas at high levels of detail can be computer intensive and time consuming. Defining multiple 2D grids with different cell sizes can significantly reduce model run times by allowing large cells to be used where fine detail is not required, such as large open rural areas, and smaller cells where more detail is needed, such as in urban areas. In this webinar we have invited guest speaker Bill Syme, expert 2D modeller and developer of the xp2D solver, to share his knowledge of 2D modelling approaches where different grid sizes are beneficial, and how to set up these models for optimum results. We discuss when and where this modelling approach is appropriate, and the pros and cons of flexible mesh versus fixed grid options. We also include a live software demonstration in xp2D showing you how quickly and easily you can build a model with different 2D domains varying in grid size, extent and orientation, and analyze the results.