Effects of the improved seaward boundary condition on the swash zone hydrodynamics with bottom resistance are investigated using the method of characteristics. The characteristic equations including the Chezy-type resistance term are solved numerically by using the specified time interval scheme. Following Guard and Baldock (2007), the improved seaward boundary condition is introduced after incorporating a parameter k. Spatiotemporal distribution of the forward and backward characteristic lines under different bottom frictions and k parameters are specified. Large k parameter postpones the swash flow reversal time and extends the entire swash duration, which enhances/reduces the function of pressure force/bottom friction in swash hydrodynamics. During the late backwash stage, the bottom resistance effect becomes less influential with the increase of parameter k. Shoreline movement is mainly controlled by the bottom friction initially, then by gravity around the swash flow reversal, and by the joint actions of bottom friction and gravity (or hydrostatic pressure and gravity) in the case of k = 0 (or k = 1) near the late backwash stage. With respect to the entire swash duration, the flow reversal time at the shoreline, the maximum run-up height and the maximum backwash velocity, it is confirmed that the effects of the boundary condition parameter k on the swash hydrodynamics become more significant under the large bottom resistance. The present study extends Deng et al. (2016)'s work with the improved seaward boundary conditions and makes it more applicable to the actual swash process. Findings from the present study could further improve our understandings of the frictional swash hydrodynamics.

采用特征法研究了改进的临海边界条件对带底部阻力的斜盘带水动力的影响。使用指定的时间间隔方案对包括 Chezy 型电阻项的特征方程进行数值求解。继 Guard 和 Baldock (2007) 之后，在引入参数k后引入了改进的向海边界条件。指定了不同底部摩擦力和k参数下前后特征线的时空分布。大k参数推迟了斜流反向时间并延长了整个斜流持续时间，这增强/减少了压力/底部摩擦力在斜流动力学中的作用。在反冲洗后期，随着参数k的增加，底部阻力效应的影响越来越小。岸线运动最初主要受底部摩擦力控制，然后在斜流反转周围受重力控制，在k  =0（或k =0 ）的情况下，受底部摩擦力和重力（或静水压力和重力）的共同作用。 = 1) 接近后期反冲洗阶段。相对于整个斜盘持续时间、岸线逆流时间、最大爬升高度和最大反冲速度，可以证实边界条件参数k对斜盘水动力学的影响在大底部阻力。本研究扩展了邓等人。(2016) 的工作改进了向海边界条件，使其更适用于实际的斜盘过程。本研究的结果可以进一步提高我们对摩擦斜盘流体动力学的理解。