Wireless Fidelity (WiFi) is the fastest growing wireless technology to date. In addition to providing wire-free connectivity to the Internet WiFi technology also enables mobile devices to connect directly to each other and form highly dynamic wireless adhoc networks. Such distributed networks can be used to perform cooperative communication tasks such ad data routing and information dissemination in the absence of a fixed infrastructure. Furthermore, adhoc grids composed of wirelessly networked portable devices are emerging as a new paradigm in grid computing. In this paper we review computational and algorithmic challenges of high-fidelity simulations of such WiFi-based wireless communication and computing networks, including scalable topology maintenance, mobility modelling, parallelisation and synchronisation. We explore similarities and differences between the simulations of these networks and simulations of interacting many-particle systems, such as molecular dynamics (MD) simulations. We show how the cell linked-list algorithm which we have adapted from our MD simulations can be used to greatly improve the computational performance of wireless network simulators in the presence of mobility, and illustrate with an example from our simulation studies of worm attacks on mobile wireless adhoc networks.