Spacing Ratio Research Articles

Axial and eccentric compressive behavior of partially encased channel–concrete composite columns with bolted connections in modular buildings

This paper introduces a novel partially encased channel–concrete composite (PECC) column for modular buildings, aiming to eliminate the need for cast-in-place concrete and facilitate rapid assembly. The PECC column consists of two prefabricated modules connected by high-strength bolts. To evaluate the column's viability, six slender specimens—one bare steel column and five composite columns—were tested under axial and eccentric compression. Variables considered included the presence of concrete, the type of transverse connections, bolt spacing, and load eccentricity ratio. The compression performance of the PECC columns was analyzed by examining their failure patterns, load–deformation responses, initial stiffness, compressive capacity, and ductility. Test results revealed that the PECC columns failed due to global buckling, concrete spalling, and crushing. The bolted connections effectively prevented module separation, enabling the PECC columns to exhibit favorable compressive behavior. The reinforced concrete encased in the channel delayed the column's buckling failure, increasing its initial stiffness and compressive capacity by 98% and 198%, respectively. Using perforated steel plates instead of transverse links between the concrete and the channel enhanced the column's initial stiffness by 20% but had little effect on its compressive capacity. Reducing the bolt spacing improved the column's initial stiffness and compression resistance by 50% and 5%, respectively. Additionally, a finite element model for the PECC columns was developed and validated against test results. Finally, simplified formulas derived from Eurocode 4 were proposed to estimate the resistance of PECC columns under axial and eccentric compression.

The impact of urban morphology on energy demand of a residential building in a mediterranean climate

This paper uniquely and systematically explores the relationship between energy performance of buildings and urban morphology by studying an existing urban fabric in a Mediterranean climate. The study took place in the city of Hebron which is geographically confined in area with continuous urbanization. Using (GIS), the K-means clustering technique was chosen to perform the statistical analysis. The coefficient variables of Floor Space Index (FSI), Ground Space Index (GSI), Open Space Ratio(OSR), and buildings’ height (L), were identified at the urban level to classify the urban tissue of the city. Accordingly, six urban patterns with equal area of 33,000 m2 were selected as representative samples of the different urban patterns of the city’s urban fabric. Then, a prototype building was placed in each of the selected patterns by the mean centre in the GIS based on the horizontal-vertical built density. Building energy simulation was performed using Design Builder software to assess the prototype’s performance. The results showed that the urban form plays a significant role in determining performance quality and energy demand. The results indicate that the cooling demand decreases when the ratio of (FSI) and (GSI) increases and when the (OSR) decreases, and vice versa in relation to the heating demand. Notably, Pattern 4, with (FSI) of 1.2, (GSI) of 0.6, (OSR) of 0.6, and (L) of 1.7, exhibited the highest heating demand at 40.3 kWh/m2/year, whereas Pattern 3, with (FSI) of 0.7, (GSI) of 0.3, (OSR) of 2.5, and (L) of 2.0, recorded the lowest at 18.6 kWh/m2/year. Conversely, Pattern 3 had the highest cooling demand, while Pattern 2, with (FSI) of 1.0, (GSI) of 0.3, (OSR) of 1.6, and (L) of 3.0, had the lowest cooling demand. To enhance energy efficiency, urban planners should consider increasing the (FSI) and (GSI) while managing the (OSR) to balance heating and cooling demands. Patterns with moderate (FSI) and (GSI) and higher (OSR) generally result in lower cooling demands and more efficient energy use. Enhancing the energy efficiency of cities should be tackled not only on the single building level but also on the urban scale. This should be addressed in urban regeneration, master plan,s and building regulations. Incorporating tools that consider the impact of all urban parameters can contribute to energy savings.

Influence of Aspect Ratio of Migration Space on Gas Migration and Accumulation Mechanisms of Different Types of Gas Reservoirs

Influence of Aspect Ratio of Migration Space on Gas Migration and Accumulation Mechanisms of Different Types of Gas Reservoirs

Improvement of mixing performance in laminar micromixers utilizing vortex-induced vibration of two circular cylinders

Micromixers have found extensive applications in various fields such as engineering, biomedicine, medical and chemistry. The utilization of vortex-induced vibration (VIV) of bluff bodies can greatly enhance fluid mixing in micromixers. This study focuses on numerically investigating the interaction between vortex-induced vibration of two cylinders, labeled Cyl-S (stationary cylinder) and Cyl-V (vibrating cylinder), and the mixing performance of micromixers. Specifically, the study examines the effects of spacing ratio (S/D) and vibration system configurations (Cyls-S+S, Cyls-S+V, and Cyls-V+V) on vibration response, near-wake structure, mixing concentration, and mixing index. The results indicate that the spacing ratio directly influences the vibration response of the cylinders, thereby significantly impacting the mixing performance. For the Cyls-V+V configuration, the downstream cylinder exhibits a considerably higher vibration amplitude compared to the upstream cylinder. Increasing the S/D ratio substantially improves the mixing effect in the Cyls-S+S configuration. For the Cyls-S+V and Cyls-V+V configurations, the enhancement of mixing due to VIV is particularly noticeable when S/D ratios of 2 and 3 are employed. The mixing index for Cyls-V+V is higher than that for Cyls-S+V within the range of 3 ≤ U⁎ ≤ 5 (where U* represents the reduced velocity). At a reduced velocity of U⁎ = 4 for Cyls-V+V, the optimal mixing indexs are found to be 0.77 (S/D = 2), 0.76 (S/D = 3), 0.78 (S/D = 4), and 0.77 (S/D = 5), respectively. However, when U⁎ = 6–10, the mixing index decreases due to the vibration of the cylinder is suppressed. Additionally, the Cyls-V+V configuration exhibits a significantly higher pressure drop within the flow channel compared to the Cyls-S+V configuration.

Effects of chamfering and spacing on aerodynamics of two tandem cylinders

The flow over two tandem cylinders is investigated with five different spacing ratios L/D = 1.25, 2.0, 3.5, 4.0, and 6.0 and four chamfered-corner ratios ξ = B/D = 0%, 5%, 10%, and 15% at a Reynolds number Re = 5300, where L, B, and D are the distance between cylinders, chamfered corner dimension, and cylinder width, respectively. This work aims to assimilate the effects of ξ and L/D on flow structures, vortex shedding, aerodynamic forces, Strouhal number, and their relationships. We identified three different flow patterns depending on ξ and L/D: overshoot flow (L/D = 1.25, ξ = 0%), reattachment flow (1.25–2.0 ≤ L/D ≤ 2.0–3.5, ξ = 0%–15%), and coshedding flow (L/D ≤ 2.0–3.5, ξ = 0%–15%). The ξ and L/D play a similar role in the qualitative change of the flow structures, albeit with different degrees. As such, when L/D or ξ is increased, an overshoot/reattachment flow may change to a reattachment/coshedding flow. With the same flow pattern, ξ has a greater influence on the aerodynamic facets than L/D. This study establishes a framework for understanding how ξ and L/D influence flow topology and aerodynamic parameters.

Numerical simulations for the flow-induced vibrations of tandem dual flexible circular cylinders

The three-dimensional large-eddy-simulation coupled with a mode superposition method was applied to numerically simulate the flow-induced vibrations (FIVs) of tandem dual flexible cylinders at Re = 1000 with three different spacing ratios (Sx/D = 2.5, 3.5, and 5, Sx is center-to-center spacing for tandem cylinders, and D is the diameter of the cylinder), corresponding to the reattachment flow, transition flow, and co-shedding flow regimes in stationary tandem cylinders, respectively. The effects of Sx/D on structural vibrations, flow fields, distributions of the surface pressures, and energy properties were investigated to reveal the mechanism for the FIV. Increasing Sx/D weakens the influence of the upstream cylinder on maximum response amplitudes and lock-in region for downstream cylinder. The wake patterns for tandem flexible cylinders are more complex compared to stationary or vibrated rigid tandem cylinders. The shielding effect reduces surface pressure on the downstream cylinder significantly when its vibrations are smaller, leading to a decrease in mean power as well. Furthermore, different mechanisms contribute to amplified FIV in downstream cylinders depending on Sx/D: when Sx/D = 2.5, the upstream vortices collide with the downstream cylinder's front surface and merge with the vortices generated by the downstream cylinder, increasing negative pressure on both front and rear surfaces of the downstream cylinders and promoting FIV; however when Sx/D =3.5 and 5, a binary vortex street forms behind the downstream cylinder without obvious negative pressures on its front surface, the dominant causes of FIV are primarily attributed to interactions among upstream and downstream vortices.

Research on the aero-hydro coupling characteristics of the floating twin-rotor wind turbine system

The concept of installing two wind turbines on a floating platform, known as a floating twin-rotor wind turbine system, has recently garnered significant interest. This configuration can harness greater wind energy resources, reduce installation and mooring costs by sharing mooring lines, and minimize losses due to wake effects between turbines through yaw control. However, previous research has not sufficiently addressed the dynamic performance analysis of such systems. This study focuses on a high-capacity floating twin-rotor wind turbine system and develops an aero-hydrodynamic coupled analysis method based on the free vortex wake method and potential flow theory, specifically tailored for the twin-rotor configuration. This method facilitates real-time iterative calculations of wind and wave loads acting on the system and suggests optimization strategies for its design. Our findings indicate that the design of high-capacity floating twin-rotor systems can significantly reduce costs. Furthermore, the twin-rotor floating system design enhances wake recovery and achieves optimal comprehensive performance when the rotor spacing ratio (S/D) is 1.2 for the IEA 15 MW turbine. The coupled interactions induce periodic variations in aerodynamic performance, with the amplitude of these variations increasing with turbulence intensity. This research lays a theoretical foundation for advancing the design, platform optimization, and coupled computational analyses of large-capacity, large-scale floating twin-rotor wind turbine systems.

Improvement of heat transfer in microchannels using nanofluids by numerical contribution on a sinusoidal shaped dissipator

This research conducts an extensive numerical investigation into the enhancement of heat transfer in wavy-walled channels using aluminum oxide-water nanofluids. The study examines the impact of key parameters, including geometric aspects (wave spacing ratio: 0-1), operational conditions (Reynolds number: 5,000-20,000), and varying nanofluid concentrations (1-6% by volume). The results indicate that zero wave spacing combined with a nanofluid concentration of 4% provides the most favorable thermal performance, resulting in a heat transfer enhancement of up to 2.5 times when compared to conventional smooth channels. While the wavy channel geometries significantly improve heat transfer, they also impose additional pressure drops, revealing a critical trade-off between enhanced thermal performance and the increased pumping power required. The study highlights the balance necessary between maximizing heat transfer and maintaining operational efficiency, particularly in systems where space is limited. These findings contribute valuable insights to the design of heat exchange systems that demand both high thermal efficiency and compact dimensions, such as those used in electronics cooling or energy-efficient HVAC systems. Additionally, the study explores the influence of the Reynolds number on both thermal and hydrodynamic behavior within the wavy channels, providing a thorough performance evaluation across different operational ranges. The conclusions drawn from this investigation offer practical guidance for optimizing heat exchanger designs, taking into account both thermal resistance and overall system performance under varying conditions.

Simulation and Experiments on Optimization of Vortex-Induced Vibration Power Generation System Based on Side-by-Side Double Blunt Bodies

In order to improve the utilization efficiency of converting low-flow current energy into electric energy for Reynolds number 10,000 ≤ Re ≤ 40,000, this paper proposes a vortex-induced vibration power generation system based on a side-by-side double blunt body. In this system, the side-by-side double blunt body structure is used in the current energy capture part to enhance the collection of low-flow current energy; the permanent magnet linear motor is used in the electric energy conversion part to improve the efficiency of electric energy conversion; and a laboratory device is constructed for testing. The effects of the blunt body structure parameters and the center spacing ratio on the energy harvesting performance of the system are qualitatively explained by constructing a simulation model. Compared with the single blunt body energy capture structure, the side-by-side double blunt body structure increases the vibration amplitude by 1.04 times and the lift by 1.14 times at the center spacing S/D = 2.4. Meanwhile, energy harvesting can be realized at a lower flow velocity, increasing the vortex-induced vibration’s energy capture range. Finally, the power generation system was experimentally verified in the laboratory, and the results showed that the vibration amplitude of the double blunt body structure was increased by 1.12 times compared to the single blunt body. The maximum output power of the generator is 10.55 W when the water velocity is 0.7 m/s. The energy conversion efficiency of the power generation system can reach a maximum of 52.93%, which is 12.33% higher than that of a single blunt body structure, which proves that the system has a higher power conversion efficiency than that of a conventional single conversion system.

Influence of submerged impingement jet designs on solar air collector performance

The present study experimentally investigates the solar air heater performance employing submerged impinging jets (SAHSIJ). The submerged jets produce high flow velocities, leading to significant turbulence aided by shear forces at the heated surface, resulting in increased and evenly distributed heat removal rates. The study explores the impact of geometric parameters viz jet spacing ratio (Sj/Dh) from 0.108 to 0.433, jet angles (α) from 75° to 90° jet diameter ratio (d/Dh) from 0.043 to 0.076, span-wise pitch ratio (Y/Dh) from 0.43 to 1.08 and stream wise pitch (X/Dh) from 0.43 to 1.73 on the Nusselt number and friction performance to enhance the overall efficacy of the system. To evaluate the effectiveness of the new SAHSIJ design in terms of thermal and thermo-hydraulic performance, the results are compared with those from a smooth duct solar air heater. The results show that the novel solar air heater with submerged pipe jet significantly outperforms the smooth duct solar air heater in terms of heat removal from the absorber plate. SAHSIJ achieved a thermal efficiency (ηth) of 75.3 % and a thermo-hydraulic efficiency (ηeff) of 69.2 %, with a thermo-hydraulic performance parameter (η) of 3.19.

A cross-scale indicator framework for the study of annual stability of land surface temperature in different land uses

Urban Land Surface Temperature (LST) is crucial in surface urban heat island (SUHI) and microclimate studies. Currently, research has focused on seasonal LST differences across land uses, but annual LST fluctuations (ΔLST) within the same land use and their drivers remain underexplored. To explore the impact of land characteristics and urban elements on seasonal LST differences, we propose annual LST stability. We constructed a new indicator framework based on Land Use and Land Cover (LULC), supplemented by Land Morphology (LM) and Land Properties (LP), for cross-scale ΔLST research. We identified land use ratios and key characteristics of urban plots with high stability. The results show an interactive effect of the green land ratio to other land on ΔLST. For residential and office land, the green space ratio (GSR) is key to annual LST stability. Residential land needs a GSR of more than 24 %. The floor area ratio (FAR) for residential and office land has a significant nonlinear effect on annual LST stability, with FARs of 1.8 for residential land and 1.5 for office land being most detrimental to the LST stability. For practical implications, we conducted cluster analyses on residential, office, and green lands, providing strategies to improve stability. These conclusions help balance land economic benefits with urban climate resilience and guide urban planning and design to address the challenges of heat and cold waves.

Investigating the Heterogeneity Effects of Urban Morphology on Building Energy Consumption from a Spatio-Temporal Perspective Using Old Residential Buildings on a University Campus

The significant increase in building energy consumption poses a major challenge to environmental sustainability. In this process, urban morphology plays a pivotal role in shaping building energy consumption. However, its impact may exhibit latent heterogeneity due to differences in temporal resolution and spatial scales. For urban energy planning and energy consumption modeling, it is crucial to pinpoint when and where urban morphology parameters matter, an overlooked aspect in prior research. This study quantitatively explores this heterogeneity, utilizing a detailed dataset from old residential buildings within a university campus. Spatial lag models were employed for cross-modeling across various temporal and spatial dimensions. The results show that annual and seasonal spatial regression models perform best within a 150 m buffer zone. However, not all significant indicators fall within this range, suggesting that blindly applying the same range to all indicators may lead to inaccurate conclusions. Moreover, significant urban morphology indicators vary in quantity, category, and directionality. The green space ratio exhibits correlations with energy consumption in annual, summer, and winter periods within buffer zones of 150 m, 50~100 m, and 100 m, respectively. It notably displays a negative correlation with annual energy consumption but a positive correlation with winter energy consumption. To address this heterogeneity, this study proposes a three-tiered framework—macro-level project decomposition, establishing a key indicator library, and energy consumption comparisons, facilitating more targeted urban energy model and energy management decisions.

Social Space Ratio: Calculating the Rate of Public Space Activities That Enhance Social Interaction on a Pedestrian Street in Karlstad, Sweden

William H. Whyte took on the challenge of assessing the amount of public space in a city based on its carrying capacity, pointing out that popular public spaces offer more room for social activities. However, the absence of qualitative characteristics makes this assessment even more challenging to implement. This study aims to find a method to gauge the carrying capacity of urban public spaces by calculating the social space ratio for pedestrian-only streets in Karlstad, Sweden, and quantifying this relationship. The social space ratio represents the proportion of public spaces that foster social interaction throughout their entire area. The method began by selecting the most relevant conceptual framework for social public spaces and then sought theory-based characteristics to assign to seven social activities on Karlstad’s pedestrian-only streets. The authors performed a comprehensive search of the literature utilizing the PRISMA approach, gathering information from credible references, placemaking toolkits, transportation toolkits, and academic sources. This was performed to determine the weighting factors and effective social areas by evaluating these activities in terms of nine categories of the chosen framework: accessibility, traffic, social infrastructure, security, places to meet, senses and experience, architecture and aesthetics, development and maintenance, and control and programming. We devised a method to calculate the carrying capacity and social space ratio of Karlstad’s pedestrian-only streets, resulting in a ratio of 0.38. The research led to the development of eight quality-control tools to analyze the seven social activities in public places. This innovative approach helps researchers and municipal planners evaluate the benefits and drawbacks of these spaces, contributing significantly to Swedish urban planning and enabling future studies to create a social area factor.

Experimental and numerical study on bubble pulsation characteristics of underwater explosions with multiple charges

This study examines the processes of expansion, merging, and collapse of multiple underwater explosion bubbles through experimental and numerical methods. A small-scale underwater explosion experiment was conducted in a water tank. The behaviors of three and four bubbles during expansion, merging, and collapse were captured using high-speed photography, and the effects of the quantity and spacing of the explosive charge on the bubble dynamics were analyzed. The results indicate that the evolution of bubble behavior in multiple charge underwater explosions, including the bubble period and radius, is significantly influenced by the spacing between charges. With a decrease in the ratio of the charge spacing to the bubble radius, the period of the merged bubble increases progressively. Independent small bubbles do not interact when the distance between charges exceeds 1.3 times the bubble radius. Furthermore, when the ratio of the spacing to the initial bubble radius (L/rb) is between 1.0 and 1.3, multiple bubbles merge during the contraction phase. When the spacing is less than the maximum radius of the bubbles, multiple bubbles inevitably merge, with fusion occurring during the expansion phase.

Secondary Skin Facade for Urban Noise Reduction: A Case Study of Bandung Creative Hub Co-working Space

Abstract In recent years, the proliferation of co-working spaces has offered a collaborative environment for entrepreneurs, freelancers, and small businesses in urban areas. However, the issue of environmental noise within these spaces presents a challenge to comfort and productivity. This study focuses on the Bandung Creative Hub (BCH), a prominent co-working space in Bandung, Indonesia, and investigates the efficacy of facade engineering solutions, particularly the installation of secondary skin, in mitigating urban noise pollution. Through a comprehensive analysis utilizing both empirical measurements and computational simulations, the study aims to understand the intricacies of noise dynamics within the BCH co-working space. Empirical measurements using the Noise Tool software capture ambient noise levels, while computational simulations with IBANA provide predictive modeling of acoustic conditions. The results reveal a significant reduction in noise levels, with the sound level around the workspace corridor decreasing by approximately 23.3%, from 62 dB to 47 dB, indicating the effectiveness of facade engineering interventions. The limitations of prior research, which concentrated solely on barrier intervention methods and spacing ratio. Nevertheless, this study introduces a fresh perspective by examining the efficacy of secondary skin facade engineering in achieving noise standards and enhancing the quality of urban environments.

Numerical Simulation and Artificial Neural Network Modeling of Cavitation on 2D Tandem Hydrofoils Arrangement

Abstract In the current research, we used a parametric approach to investigate cavitation with tandem-arranged Clark Y-11.7% hydrofoils. We simulated the tandem-arranged hydrofoil system using ANSYS FLUENT with the Zwart cavitation model combined with the Transition SST turbulence model. To substantiate the accuracy and reliability of the numerical model, computations were performed for an individual Clark Y-11.7% hydrofoil and compared to experimental results. The following parameters were studied in tandem arrangement: cavitation number(σ), horizontal direction spacing ratio between two hydrofoils(x), vertical direction spacing ratio between two hydrofoils(y), angle of attack (AOA) of the upstream hydrofoil (α 1), and angle of the downstream hydrofoil relative to the upstream hydrofoil (α 2). The lift coefficient (C L) was used to estimate due to the acceptable error. An optimal artificial neural network (ANN) model was trained based on the five-parameter combination from numerical simulations. The model’s weights and biases were presented, providing a prediction method for hydrofoils in tandem arrangement with cavitation. A global sensitivity analysis based on the trained model is implemented, which reveals the AOA of the downstream hydrofoil (α 2), the horizontal spacing ratio (x), and the AOA of the upstream hydrofoil (α 1) have a main effect on the performance of the tandem arrangement.

Vortex-induced vibrations of three rigidly coupled circular cylinders in an equilateral-triangular arrangement

A three-cylinder system in an equilateral-triangular arrangement is a common, basic structure in the engineering field, and the rigid connection of multiple cylinders has been applied in some practical projects. In this paper, three cylinders in an equilateral triangle arrangement for a spacing ratio of 4 at Reynolds number of 200 are studied by means of numerical simulation. The vibration modes are divided into single cylinder vibration, three freely vibrating vibration and three rigidly coupled vibration. The vortex-induced vibration characteristics and aerodynamic forces and fluid–structure-interaction mechanisms are analyzed. The results show that the vibration velocity regions and the amplitude of three freely vibrating cylinders in the transverse and streamwise directions are obviously larger than that of a single cylinder. The rigid connection measures can effectively suppress the vibration velocity region and amplitude. However, this suppression effect is no better than the single cylinder. In the lock-in region, the trajectories of three rigidly coupled cylinders are regular closed shapes. The Strouhal numbers of the three cylinders are synchronous in the natural frequency in the lock-in region. The wake vortices from the upstream cylinders affect the downstream cylinders, which depends on different case and reduced velocity. The complex aerodynamic interference and parallel vortices of the wake enhance the vibration of the structure in some cases.

Decline in Isotope Dilution Space Ratio Above Age 60 Could Affect Energy Estimates Using the Doubly Labeled Water Method

BackgroundDoubly labeled water is gold standard for measuring total energy expenditure (TEE). Measurements using the method are sensitive to the isotope dilution space ratio (DSR). Accuracy and precision of the method might be improved if we could identify factors influencing DSR. ObjectivesWe evaluated the potential associations of age, sex, ethnicity, anthropometry, body composition, turnover rates of the isotopes, and geographical elevation with DSR. MethodsWe used univariate regression analysis to explore the relationships between the continuous variables and analysis of variance to test the relationships between the categorical variables with DSR. Subsequently, we used general linear model (GLM) and 1-way analysis of variance to evaluate the simultaneous associations of age, sex, ethnicity, fat-free mass (FFM) and fat mass (FM) on DSR. ResultsFrom 5678 measurements complied from studies around the world with diverse ethnicity and living at various elevations, the mean DSR was 1.0364 ± 0.0141. No meaningful physiologic effect of any of the continuous and categorical variable on DSR was detected. General linear model analysis revealed no effect of FFM and FM (P > 0.33) on DSR, but DSR decreased with age (P < 0.001) among those aged 60 y and older regardless of sex. Among the Whites who were younger than 60 y, DSR was not related to FFM and FM (P = 0.73) but was affected by both age and sex (P < 0.001). ConclusionsPrevious estimates of age-related decline in TEE may have overestimated TEE at age 90 y. Validation studies on older participants are required to confirm this finding.

Determining the Effect of Green Space Ratio and Urbanization on the Land Surface Temperature, a Case Study in the Istanbul Metropolitan

Determining the Effect of Green Space Ratio and Urbanization on the Land Surface Temperature, a Case Study in the Istanbul Metropolitan

Experimental Study of the Random Wave-Induced Hydrodynamics and Soil Response in a Porous Seabed Around Double Piles

The evaluation of the wave-induced pore pressures around the offshore piles has attracted great attentions among coastal engineers, because they have been commonly used as foundations of numerous marine infrastructures. This paper presents comparative studies of the random wave-induced transient seabed response around single and double piles in a sandy seabed through a series of wave flume experiments. The influences of relative spacing ratios, wave incidence angles, and front pile diameters under different random wave parameters on oscillatory pore pressures in the vicinity of double piles are examined. In addition, variations in wave profiles and dynamic wave pressures surrounding single and double piles are quantitatively analyzed. Based on the experimental results, the following conclusions can be drawn: (1) under the influence of random waves, the wave profiles around the double piles exhibit obvious irregularity and nonlinearity; (2) the shielding effect existing in the tandem piles results in lower dynamic wave pressures around the rear pile compared to the front pile; (3) the pore pressures on the front surface of the double piles decrease with increasing soil depth, with a decreasing attenuation rate at each layer; (4) when the relative spacing ratio G/D2=3, the group-pile effect weakens, leading to an increase in the pore pressures around the rear pile, approaching the results of a single pile under conditions of lower significant wave heights or periods; (5) the intense disturbance effect caused by large wave incidence angles exacerbates the pore pressure response around the double piles; (6) when the diameter of the front pile in the tandem piles increases, it enhances the shielding effect, thus suppressing the seabed response around the rear pile. In contrast, it causes an increase in the wave surface around the double piles, exacerbating the pore pressure response in the seabed. The latter effect becomes more pronounced when the significant wave height is larger.