Spatial Decay Bounds for the Brinkman Fluid Equations in Double-Diffusive Convection

In this paper, we consider the Brinkman equations pipe flow, which includes the salinity and the temperature. Assuming that the fluid satisfies nonlinear boundary conditions at the finite end of the cylinder, using the symmetry of differential inequalities and the energy analysis methods, we establish the exponential decay estimates for homogeneous Brinkman equations. That is to prove that the solutions of the equation decay exponentially with the distance from the finite end of the cylinder. To make the estimate of decay explicit, the bound for the total energy is also derived.

PERENCANAAN SISTEM PLAMBING DAN HIDRAN KEBAKARAN PADA PROYEK PEMBANGUNAN HOTEL PESONA ALAM

Hotel Pesona Alam merupakan salah satu hotel yang terletak di kawasan Cisarua, Bogor. Perencanaan system plambing dan Hidran Kebakaran yang memadai diperlukan untuk menunjang kenyamanan dan keamanan aktivitas pengunjung Hotel. Perhitungan perencanaan air bersih maupun kotor, digunakan metode Unit Beban Alat Plambing. Penggambaran isometri jaringan perpipaan dan penentuan diameter pipa air bersih dibantu dengan software Pipe Flow Expert. Berdasarkan perhitungan, didapatkan kebutuhan air bersih per hari pada Hotel Pesona Alam adalah 230 m3/hari dengan diameter pipa air bersih yang diperlukan sebesar 0.5”, 0.75”, 1”, 1.25”, dan 2”. Perkiraan air buangan yang dihasilkan sebesar 207 m3/hari dengan diameter air buangan yang digunakan sebesar 1.25”, 1.5”, 2”, 2.5”, 3” dan 4”. Sedangkan untuk sistem hidran kebakaran digunakan 3 jenis hidran kebakaran yaitu pillar hydrant, fire hose reel, dan sprinkler. Kebutuhan air bersih untuk pemadam kebakaran sebesar 270 m3.

Ultrasonic Measurement for the Experimental Investigation of Velocity Distribution in Vapor-Liquid Boiling Bubbly Flow

This study proposes an ultrasonic velocity profiler (UVP) with a single ultrasonic gas-liquid two-phase separation (SUTS) technique to measure the velocity distribution of vapor-liquid boiling bubbly flow. The proposed technique is capable of measuring the velocity of the vapor bubble and liquid separately in boiling conditions. To confirm the viability of the measurement technique, the experiment is conducted on vertical pipe flow apparatus. The ultrasonic transmission and effect of ultrasonic refraction through the pipe wall and water are investigated at ambient temperature until subcooled boiling temperature is reached. The velocity profile in the water at elevated temperature is measured to verify the ability of the technique in this application. The bubbly flow velocity distribution measurement in boiling conditions is then demonstrated. The results show that the proposed technique can effectively investigate the velocity of both phases under various fluid conditions in boiling bubbly flow.

Numerical investigation of semifilled-pipe flow

This study describes turbulent flow in a semifilled pipe with a focus on its secondary currents. To the authors’ knowledge, we provide the first highly resolved data-set for semifilled-pipe flow using direct numerical simulation. The flow parameters range from $Re_\tau =115$ , just maintaining turbulence, to moderate turbulent flow at $Re_\tau =460$ . Some of the main flow characteristics are in line with previously published results from experiments, such as the velocity-dip phenomenon, the main secondary flow and the qualitative distribution of the Reynolds stresses in the core of the flow. We observe some flow phenomena which have not yet been reported in the literature so far for this type of flow. Among those is the inner secondary cell in the mixed corner between the free surface and the pipe's wall, which plays a major role in the distribution of the wall shear stress along the perimeter. We observe that the position and extension of the inner vortex scale with the wall shear stress and those of the outer vortex scale with outer variables. For the first time, we present and discuss distributions of the complete Reynolds stress tensor and its anisotropy which gives rise to the generation of mean streamwise vorticity in a small region in the mixed corners of the pipe. Mean secondary kinetic energy, however, is generated at the free surface around the stagnation point between the inner and outer vortices. This generation mechanism is in line with a vortex dynamics mechanism proposed in the literature.