A、<span style="font-size: 10.5pt; font-family: 宋体;">层流底层,使流体处于层流状态</span>
B、<span style="font-size: 10.5pt; font-family: 宋体;">流体湍动区域,使层流底层减薄</span>
C、<span style="font-size: 10.5pt; font-family: 宋体;">层流底层,提高流体湍动程度</span>
D、<span style="font-size: 10.5pt; font-family: 宋体;">流体过渡区域,提高流体湍动程度</span>
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