Abstract In this paper two immersed boundary methods (IBM), specifically a continuous forcing method (CFM) and a discrete forcing method (DFM), are applied to perform direct numerical simulations (DNSs) of heat transfer problems in tubular fluid-particle systems. Both IBM models are built on the well-developed models utilized in momentum transfer studies, and have the capability to handle mixed boundary conditions at the particle surface as encountered in industrial applications with both active and passive particles. Following a thorough verification of both models for the classical Graetz-Nusselt problem, we subsequently apply them to study a much more advanced Graetz-Nusselt problem of more practical importance with a dense stationary array consisting of hundreds of particles randomly positioned inside a tube with adiabatic wall. The influence of particle sizes and fractional amount of passive particles is analyzed at varying Reynolds numbers, and the simulation results are compared between the two IBM models, finding good agreement. Our results thus qualify the two employed IBM modules for more complex applications.

中文翻译：

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从动量传递到热传递 - 使用浸入边界方法对高级 Graetz-Nusselt 问题的比较研究

摘要 在本文中，两种浸入边界方法 (IBM)，特别是连续强迫方法 (CFM) 和离散强迫方法 (DFM)，被应用于对管状流体粒子系统中的传热问题进行直接数值模拟 (DNS)。两个 IBM 模型都建立在动量传递研究中使用的成熟模型之上，并且能够处理颗粒表面的混合边界条件，如工业应用中遇到的主动和被动颗粒。在对经典 Graetz-Nusselt 问题的两个模型进行彻底验证之后，我们随后将它们应用于更高级的 Graetz-Nusselt 问题，该问题具有更实际的重要性，其中密集的静止阵列由数百个随机放置在绝热管内的粒子组成。墙。在不同的雷诺数下分析了粒径和被动粒子分数的影响，并比较了两个 IBM 模型之间的模拟结果，发现了良好的一致性。因此，我们的结果使两个采用的 IBM 模块适合更复杂的应用程序。