LBHydra is a modular, extensible Lattice-Boltzmann simulation package capable of modeling a wide array of fluid mechanical behavior. The Lattice-Boltzmann methods provided with LBHydra are capable of simulating laminar and turbulent flows, heat and mass transport, and multiple phase and multiple component fluids in complex and changing fluid flow geometries. The simulation engine offers numerous areas for user input and modification, including user-defined material modules, lattice-types and subroutines, thus enabling far more complex simulations. Furthering the benefit of modularity is the ability to couple LBHydra with other applications, either by linking to the simulation engine directly or by employing LBHydra’s libraries within an application. Additional modules provided with the simulator allow the user to harness the power of CUDA-compliant nVIDIA graphics processing units (GPUs). These modules transfer the calculation from CPU to GPU, with the potential to accelerate simulations up to 40x faster.