Experiments on the non-Boussinesq gravity currents generated from an instantaneous buoyancy source propagating on an inclined boundary in the slope angle range
$0^{\circ } \le \theta \le 9^{\circ }$
with relative density difference in the range of
$0.05 \le \epsilon \le 0.17$
are reported, where
$\epsilon = (\rho _1-\rho _0)/\rho _0$
, with
$\rho _1$
and
$\rho _0$
the densities of the heavy and light ambient fluids, respectively. We showed that a
$3/2$
power-law,
${(x_f+x_0)}^{3/2}= K_M^{3/2} {B_0'}^{1/2} (t+t_{I0})$
, exists between the front location measured from the virtual origin,
$(x_f+x_0)$
, and time,
$t$
, in the early deceleration phase for both the Boussinesq and non-Boussinesq cases, where
$K_M$
is a measured empirical constant,
$B_0'$
is the total released buoyancy, and
$t_{I0}$
is the
$t$
-intercept. Our results show that
$K_M$
not only increases as the relative density difference increases but also assumes its maximum value at
$\theta \approx 6^{\circ }$
for sufficiently large relative density differences. In the late deceleration phase, the front location data deviate from the
$3/2$
power-law and the flow patterns on
$\theta =6^{\circ },9^{\circ }$
slopes are qualitatively different from those on
$\theta =0^{\circ },2^{\circ }$
. In the late deceleration phase, we showed that viscous effects could become more important and another power-law,
${(x_f+x_0)}^{2}= K_{V}^{2} {B_0'}^{2/3} {{A}^{1/3}_0} {\nu }^{-1/3} (t+t_{V0})$
, applies for both the Boussinesq and non-Boussinesq cases, where
$K_V$
is an empirical constant,
$A_0$
is the initial volume of heavy fluid per unit width,
$\nu $
is the kinematic viscosity of the fluids, and
$t_{V0}$
is the
$t$
-intercept. Our results also show that
$K_V$
increases as the relative density difference increases and
$K_V$
assumes its maximum value at
$\theta \approx 6^{\circ }$
.