FEATool Multiphysics is an easy-to-use FEA and CFD Simulation Toolbox
A simulator for drones, cars and more, built on Unreal Engine
Real-time interactive 3D graphics API for scientific simulations
AVR simulator IDE
Hackerando la Macchina Ridotta (Hacking the Smaller Machine)
LIME is a software tool for creating multiphysics simulation codes.