A transient numerical investigation has been conducted to determine the thermal effects of an axisymmetric oil jet impinging on a high-speed reciprocating disc subjected to uniform heat flux and bounded by a cylindrical wall. The two-phase air-oil simulations are performed using the volume of fluid (VOF) method with a high-resolution interface-capturing scheme. The three-dimensional Navier-Stokes equations and energy equation are numerically solved using a finite volume discretization. The conjugate heat transfer (CHT) method is used to obtain a coupled heat transfer solution between the disc and fluid, yielding a more accurate prediction for the heat transfer coefficient. To overcome the high computational cost of such a simulation, a new methodology is presented to accelerate the solution. The simulation process involves several stages, including the simulation of the heat transfer of a stationary disc with a cooling jet at different impingement distances from the nozzle exit and simulation of a moving disc without the cooling jet and subjected to constant heat flux. Following this, the flow field and thermal characteristics of a reciprocating disc with constant heat flux and an impinging cooling jet is considered. For jet impingement Onto the moving boundary, the maximum Nusselt number is achieved a short time after the relative velocity between the disc and the jet reaches its maximum. (C) 2014 Elsevier Ltd. All rights reserved.