The unified gas kinetic scheme (UGKS) is a powerful method to simulate microscale gas flows. However, due to the lack of corresponding specified heat flux boundary (SHFB) treatment, there is great difficulty for UGKS to simulate problem with SHFB. In this paper, a SHFB treatment for UGKS is proposed based on gas kinetic theory. In the proposed boundary treatment, the heat flux term is directly added into the gas kinetic conservation equation of heat flux on boundary. In this conservation equation, the heat flux transferring from gas to the boundary is calculated using an extrapolated distribution function of inside gas, and the heat flux transferring form boundary to the gas is calculated using an equilibrium rebounding distribution function. Using the conservation equation of mass on boundary to close conservation equations, the gas density and temperature terms for rebounding gas distribution function can be calculated simultaneously. Distribution function on SHFB is reconstructed using rebounding gas distribution function and extrapolated distribution function of inside gas. Fluxes of gas distribution function and macro variables on SHFB is calculated with the reconstructed distribution function. Typical benchmark cases including steady and unsteady Fourier flow, steady Couette flow, pressure-driven flow, cavity flow and supersonic flow around square cylinder are tested to validate the proposed boundary treatment. The validations prove the accuracy, reliability and universality of the proposed method.

统一气体动力学方案 (UGKS) 是模拟微尺度气体流动的有力方法。然而，由于缺乏相应的指定热通量边界（SHFB）处理，UGKS很难模拟SHFB问题。本文提出了一种基于气体动力学理论的 UGKS 的 SHFB 处理方法。在所提出的边界处理中，热通量项被直接添加到边界上热通量的气体动力学守恒方程中。在这个守恒方程中，从气体到边界的热通量是使用外推的内部气体分布函数计算的，从边界到气体的热通量是使用平衡回弹分布函数计算的。使用边界质量守恒方程来闭合守恒方程，可以同时计算反弹气体分布函数的气体密度和温度项。SHFB上的分布函数是利用反弹气体分布函数和外推气体分布函数重构的。用重构的分布函数计算SHFB上的气体分布函数和宏观变量的通量。测试了典型的基准案例，包括稳态和非稳态傅里叶流、稳态库埃特流、压力驱动流、腔流和方柱周围的超音速流，以验证所提出的边界处理。验证证明了所提方法的准确性、可靠性和普遍性。SHFB上的分布函数是利用反弹气体分布函数和外推气体分布函数重构的。用重构的分布函数计算SHFB上的气体分布函数和宏观变量的通量。测试了典型的基准案例，包括稳态和非稳态傅里叶流、稳态库埃特流、压力驱动流、腔流和方柱周围的超音速流，以验证所提出的边界处理。验证证明了所提方法的准确性、可靠性和普遍性。SHFB上的分布函数是利用反弹气体分布函数和外推气体分布函数重构的。用重构的分布函数计算SHFB上的气体分布函数和宏观变量的通量。测试了典型的基准案例，包括稳态和非稳态傅里叶流、稳态库埃特流、压力驱动流、腔流和方柱周围的超音速流，以验证所提出的边界处理。验证证明了所提方法的准确性、可靠性和普遍性。测试了方形圆柱周围的压力驱动流动、腔流动和超音速流动，以验证所提出的边界处理。验证证明了所提方法的准确性、可靠性和普遍性。测试了方形圆柱周围的压力驱动流动、腔流动和超音速流动，以验证所提出的边界处理。验证证明了所提方法的准确性、可靠性和普遍性。