Water management remains one of the major challenges in optimising the performance of PEMFCs, in which liquid accumulation and removal in gas diffusion layers (GDLs) and flow channels should be addressed. Here, effects of GDL surface roughness on the water droplet removal inside a PEMFC flow channel have been investigated using the Volume of Fluid method. Rough surfaces are generated according to realistic GDL properties by incorporating RMS roughness and roughness wavelength as the main characteristic parameters. Droplet dynamics including emergence, growth, detachment, and removal in flow channels with various airflow rates are simulated on rough substrates. The influences of airflow rate on droplet dynamics are also discussed by comparing the detachment time and droplet morphology. The liquid removal efficiency subject to different surface roughness parameters is evaluated by droplet detachment time and elongation, and regimes of detachment modes are identified based on the droplet breakup location and detachment ratio. The results suggest that rough surfaces with higher RMS roughness can facilitate the removal of liquid inside flow channel. Whilst surface roughness wavelength is found less significant to the liquid removal efficiency. The results here provide qualitative assessments on identifying the key surface characteristics controlling droplet motion in PEMFC channels.

水资源管理仍然是优化PEMFC性能的主要挑战之一，应解决气体扩散层（GDL）和流动通道中的液体积聚和去除问题。在这里，已经使用流体体积法研究了GDL表面粗糙度对PEMFC流道内水滴去除的影响。通过将RMS粗糙度和粗糙度波长作为主要特征参数，根据实际GDL属性生成粗糙表面。在粗糙的基材上模拟了液滴动力学，包括具有各种气流速率的流道中的出现，生长，分离和去除。通过比较分离时间和液滴形态，还讨论了气流速率对液滴动力学的影响。通过液滴的剥离时间和伸长率来评价在不同的表面粗糙度参数下的液体去除效率，并基于液滴的破裂位置和剥离率来确定剥离方式。结果表明，具有较高RMS粗糙度的粗糙表面可以促进流道内部液体的去除。尽管发现表面粗糙度波长对液体去除效率影响不大。这里的结果为定性评估提供了确定PEMFC通道中控制液滴运动的关键表面特性。结果表明，具有较高RMS粗糙度的粗糙表面可以促进流道内部液体的去除。尽管发现表面粗糙度波长对液体去除效率影响不大。这里的结果为定性评估提供了确定PEMFC通道中控制液滴运动的关键表面特性。结果表明，具有较高RMS粗糙度的粗糙表面可以促进流道内部液体的去除。尽管发现表面粗糙度波长对液体去除效率影响不大。这里的结果为定性评估提供了确定PEMFC通道中控制液滴运动的关键表面特性。