It is shown that quasi‐one‐dimensional computational techniques can be successfully used to model the flow in large, geometrically complicated shock tubes. Such shock tubes, or blast simulators, can be used to simulate nuclear or conventional explosions by shaping the pressure history. Results from computations show favorable agreement when compared with data taken in a blast simulator facility in Gramat, France. It is furthermore shown how relatively simple computational tools can be used to design large blast/thermal simulators.