In the pursuit to improve thermal and fuel efficiencies of internal combustion engines, various engine designs and configurations have been developed over recent years. Since the progress in this field keeps on increasing continuously, the geometrical aspects of combustion chamber and the engine configurations and their effects on the in-cylinder air/fuel mixing, turbulence and fuel combustion are becoming more relevant than ever. Due to this, there lies an impending need for a critical analysis of current in-cylinder flow analysis techniques available, their application on different engine types and the results acquired from the studies. Several new flow measurement technologies have emerged and for the past ten years, a critical analysis of airflow capturing methods within IC engines has not been done despite its great significance. This review presents a short yet a meaningful understanding to the analysis techniques for engine in-cylinder flows during the intake and compression of air and fuel, while bringing out significant findings from individual works, resulting in pointing out the strengths and accuracies of these techniques. In the reflection of reviewed studies, explicit analytical schemes and formulations bearing least errors compared to experimental results, are suggested. © 2021 THE AUTHORS