Intensive quenching is a fast transient thermal process where an austenitized part is cooled rapidly by contact with a stream of high velocity water. As in all quenching processes, the quenchant flow condition has a primary effect on material response, including the final microstructural phase distribution, hardness, residual stress, and distortion. Therefore, characterization of the quenchant flow is important for understanding the quenching process and the relationships between quenchant flow rate, part cooling rate, material phase transformations, and residual stress. With the development of high-speed computer and computational fluid dynamics (CFD) technologies, the quenchant flow pattern around a complex part during quenching can be calculated. This allows the local heat transfer between the quench media and the part to be calculated. The transient heat transfer coefficients predicted from such a CFD model can then be used in a finite element based thermal-stress calculation to predict the final residual stress state of the part, as well as the microstructural phase distribution, hardness distribution, and dimensional change due to quenching. In this paper, transient CFD analyses using FLUENT are applied to characterize the water flow and thermal boundary conditions around a spur gear made of carburized Pyrowear 53 during intensive quenching. The calculated heat transfer coefficients are imported to DANTE heat treatment models, and the gear's response to intensive quenching is predicted. The results include hardness, phase transformation, stress, and distortion. The relationships between temperature field, phase transformation, residual stress, and distortion during quenching are explained using the modeling histories. The combination of FLUENT and DANTE models provides efficient and effective solutions to the quenching fixture and water flow designs. The predicted gear distortion and residual stresses are validated using experiments.