Computer Fluid Dynamic (CFD) approaches have increasingly been developed and applied to simulate water-related natural hazards (e.g., flood and landslide induced hazards). In order to explore different risk scenarios and potential risk-reduction options, the development of fast running models represents an important task to face. Thus, numerical modeling may be suitable to support risk analysis useful for risks assessment and reduction and to address hazard related uncertainty.

Computational methods to simulate complex nonlinear flow and transport processes as well as multiphase flow are more and more relevant for advanced applications related to natural hazards such as scouring around complex hydraulic structures, dam and dyke failures, sediment and solid debris transport in rivers, slope stability, triggering and propagation of landslides, rainfall induced landslides, and landslide generated water waves.

Several numerical approaches, with varying degrees of complexity, exist to simulate water-sediment coupled dynamics by solving the governing equations of fluid motion: next to wide utilized structured mesh (rectangular grids), unstructured mesh (triangular grids), and, most recently, flexible mesh models, the use of mesh-free methods (Smoothed Particle Hydrodynamics, Moving Particle Semi-implicit, material point method, Lattice Boltzmann, Discrete Element Method, etc.) and coupled models for CFD has grown exponentially during the last decade, especially for those applications involving fast multiphase flow with violent impact, rapidly moving interfaces, and severe discontinuities at the interface.

The main aim of this special issue is to highlight the most recent advances in CFD modeling of water-related natural hazards and to discuss their future developments. Special focus is devoted to the modeling and handling of uncertainty in order to identify proper strategies. The special issue welcomes applications to relevant problems of practical and theoretical interest, as well as the validation of new mathematical models against benchmark test cases. The special issue encourages the submission of articles focusing on the application on articles in the field of hydraulic engineering with particular attention to validation and accuracy of simulations.

Potential topics include but are not limited to the following:

• Modelling and simulation of river floods, dam and dyke failure, and landslides propagation
• Multiphase flow in turbulent transport processes and flow stability problems
• Novel CFD methods (mesh- or particle-based) or coupled models and applications for free surface flows
• Wave interaction with structures and floating debris
• Development and validation of open sources CFD codes for hydraulic engineering problems
• Implementation of high performance computing in CFD including GPU computing