DESIGN, INSTALLATION, CAPACITIES AND EXPENSES OF AN INDOOR MULTIPURPOSE MODULAR 2D WAVE FLUME AND CIRCULATING WATER CHANNEL
Authors: BIDAGUREN IÑIGO , MONTALBAN NATALIA , IZQUIERDO URKO , ALBAINA IÑIGO , PEÑA ALBERTO , URTARAN EGOITZ , BLANCO JESUS MARIA 
Published: September 2023

In this article all the details related to the design, installation process, working capacities and expenses of a modular indoor laboratory flume are presented. The facility is able to work as wave flume or circulating water channel. Flume structure design  distributes appropriately the load, to ensure the structural safety of the building. The length of the wave flume depends on the number of these structures, 2.5 m each, which are attached one to each other. Presented cases are 12.5 m and 25 m length. Width is 600 mm and can be filled up to 700 mm water depth. In this work, a multipurpose 50 m3 underground water storage tank is used to feed the flume through three centrifugal pump pressure group equipped with a variable frequency drive. Main structure is made of a welded stainless steel square-tubular frame. Seabed is flat, made from a folded stainless steel 5 mm sheet metal and a sandwich-type assembly system allows the fitting of the lateral glasses to the seabed frame. A fine-tuning regulation system allows a perfect alignment of each of the modules with the adjacent. This manufacturing and assembly strategy avoids undesirable whirls effects. Two types of wave generators have been tested, an in-house developed one for regular waves and an externally manufactured one with added options: irregular waves, and active absorption system of reflected waves. At the end of the flume, a parabolic beach has been installed as wave energy dissipation system. An in-house developed regulation system sets the optimal position of this device. Several dissipation options have been tested: height, slopes and perforated surfaces. A foldable wave generator paddle and a set of pipes and valves, allows working as water channel by recirculating water to the underground storage tank, and therefore, increasing flume research versatility. In the upper part, there have been mounted guides along the whole facility so that different ad-hoc devices can be attached onto it, such as testing models or necessary instrumentation. Among this, we can mention wave gauge module together with resistive wave gauges; digital, ultra-low pressure sensor that is fully conditioned and temperature compensated; CompactRIO controller as data acquisition system (National Instruments, cRIO-9063 model) with an inputs voltage module (National Instruments-9205, C-series). A computer with a Labview program that has been developed specifically for that purpose controls all data recording. In addition, the expenses of the main components are also presented, which demonstrate the cost effective of this indoor laboratories where small scale models can be tested. In this work the design characteristics and operation of the main components of the wave flume, such as the wave-maker, wave absorber, wave probes and data acquisition system are reported in detail together with the full range of wave parameters achievable in any experimental campaign in the Le Méhauté chart. This technical recommendations provides any research group with useful guidelines and details necessary to construct their own domestic wave flume being good value for money and unachievable otherwise.