Flow and heat transfer in a bidisperse gas–solid system with freely moving spheres are simulated by particle-resolved direct numerical simulation (PR-DNS). Gas–solid coupling is enforced by the direct-forcing immersed boundary method. Compard with the DNS database, it is found that the existing polydisperse drag correction model developed from static systems combined with various monodisperse drag models underestimates the drag force on dynamic arrays of particles. The existing Nusselt number correction model developed from static systems combined with various monodisperse models overestimates the Nusselt number of dynamic arrays of particles. Sensitivity analysis indicates that the effects of the granular temperature on the drag force and Nusselt number are negligible. Novel polydisperse drag and Nusselt number models are derived based on the database. The advantages of the derived polydisperse drag and Nusselt number models are demonstrated and confirmed by comparing the results of the computational fluid dynamics–discrete element method using various drag and Nusselt number models with experimental or additional PR-DNS data.

中文翻译：

---

基于双分散气固系统直接数值模拟的新型阻力和努塞尔数模型

通过粒子分辨直接数值模拟 (PR-DNS) 模拟具有自由移动球体的双分散气固系统中的流动和传热。气固耦合通过直接强制浸入边界法进行。与DNS数据库比较发现，现有的由静态系统结合各种单分散阻力模型发展起来的多分散阻力修正模型低估了动态颗粒阵列上的阻力。现有的由静态系统与各种单分散模型相结合开发的努塞尔数校正模型高估了动态粒子阵列的努塞尔数。敏感性分析表明颗粒温度对曳力和努塞尔数的影响可以忽略不计。基于该数据库推导出新颖的多分散阻力和努塞尔数模型。通过将使用各种阻力和努塞尔数模型的计算流体动力学离散元方法的结果与实验或附加 PR-DNS 数据进行比较，证明并证实了所导出的多分散阻力和努塞尔数模型的优点。