How slip length influences wall shear stress from jetting cavitation bubbles

Boundary slip can strongly influence the wall shear stress generated by a collapsing cavitation bubble near a solid surface. Here, we investigate this effect by systematically varying slip length

and bubble stand-off distance

gamma γ $\gamma$

. We show that boundary slip has negligible influence on bubble dynamics and jet formation prior to jet impact, but markedly alters the near-wall flow during jet spreading. Increasing

l l $l$

substantially reduces both outward and inward peak shear stresses, suppresses flow separation during fast jet spreading and reorganises the spatio-temporal stress distribution. We derive a scaling for the maximum outward stress

tau Subscript m τ m $\tau _m$

with

tau Subscript m Baseline almost equals mu upper U 0 upper R e Superscript 0.5 Baseline left parenthesis upper U Subscript e Baseline divided by upper U 0 right parenthesis Superscript 1.5 Baseline divided by left parenthesis 0.3 upper R Subscript italic max Baseline plus l left parenthesis upper U Subscript e Baseline upper R e divided by upper U 0 right parenthesis Superscript 0.5 Baseline right parenthesis τ m ≈ μ U 0 R e 0.5 ( U e / U 0 ) 1.5 / ( 0.3 R max + l ( U e R e / U 0 ) 0.5 ) $\tau _m\approx {\mu {U}_{0}{Re}^{0.5}(U_e/{U}_{0})^{1.5}}/ ({0.3R_{\textit{max}}+l(U_e {Re}/{U}_{0})^{0.5}})$

, which captures the coupled effects of slip length, maximum bubble radius

upper R Subscript italic max R max $R_{\textit{max}}$

and the outer-edge velocity

upper U Subscript e U e $U_e$

of the spreading wall jet. Combined with a scaling for

upper U Subscript e U e $U_e$

in terms of

gamma γ $\gamma$

and

l l $l$

, this yields a semi-empirical predictive framework for the maximum wall shear stress. These results clarify how interfacial slip regulates extreme cavitation-driven shear and offer a basis for its prediction and control.