| Summary: | The influence of apex angle and tilting angle on droplet spreading dynamics after impinging on wedge-patterned biphilic surface has been experimentally investigated. Once the droplet contacts the wedge-patterned biphilic surface, it spreads radially on the surface, with a tendency toward a more hydrophilic area. After reaching the maximum spreading diameter, the droplet contracts back. From the experimental results, the normalized diameter <inline-formula> <math display="inline"> <semantics> <mi>β</mi> </semantics> </math> </inline-formula> (<inline-formula> <math display="inline"> <semantics> <mrow> <mi>β</mi> <mo>=</mo> <mi>D</mi> <mo>/</mo> <msub> <mi>D</mi> <mn>0</mn> </msub> </mrow> </semantics> </math> </inline-formula>) was found to be related with the Weber number (<inline-formula> <math display="inline"> <semantics> <mrow> <mi>W</mi> <mi>e</mi> <mo>=</mo> <mi>ρ</mi> <mi>D</mi> <msup> <mi>V</mi> <mn>2</mn> </msup> <mo>/</mo> <mi>γ</mi> </mrow> </semantics> </math> </inline-formula>) as <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mi>β</mi> <mrow> <mi>max</mi> </mrow> </msub> <mo>∼</mo> <mi>W</mi> <msup> <mi>e</mi> <mrow> <mn>1</mn> <mo>/</mo> <mn>5</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula>. during the first spreading process. Below 67.4°, a larger apex angle can help a droplet to spread on the surface more quickly. The maximum spreading diameter has a tendency to increase with the Weber number, and then decrease after the Weber number, beyond 2.7. Approximately, the critical Weber number is about 5, when the droplet lifts off the surface. Considering the effect of apex angle, the maximum normalized spreading diameter has a rough expression as <inline-formula> <math display="inline"> <semantics> <mrow> <mi>β</mi> <mo>∼</mo> <msqrt> <mrow> <mi>α</mi> <mi>τ</mi> </mrow> </msqrt> </mrow> </semantics> </math> </inline-formula>
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