Methods, systems, and apparatus, including computer programs encoded on computer storage media, for processing data representing the effect of tortuosity on the acoustic behavior of a fluid in a porous medium. One of the methods includes generating by a first data processing program of the data processing apparatus, a model of acoustic behavior of a fluid in a porous medium including an effect of tortuosity, with the model comprising a time variable indicative of a sound speed of the fluid. The method includes rescaling the time variable of the model based on the sound speed in a fluid in the porous medium. The method also includes simulating the acoustic behavior including the effect of tortuosity of the porous medium based on the rescaling of the time-related variables within the model.