An assessment of the current thermal modeling methodologies for data centers is presented, with focus on the use of computational fluid dynamics and heat transfer as analysis tools, and model validation. Future trends in reduced or compact modeling of data center airflow and heat transfer are presented to serve as an overview of integrating rack-level compact models into full-scale facility level numerical computations. Compact models can be used to efficiently model data centers through varying model fidelity across length scales. Dynamic effects can be included to develop next-generation control schemes to maximize data center energy efficiency.