The Research On The Cooling Effect Of Lake And Its Scenario Simulation In High-density Built-up Area

High-speed urbanization and large-scale urban expansion have made urban problems prominent,among which the urban heat island effect makes many large and medium-sized cities become the veriTablele "furnace" in summer.As an important part of urban ecological space,urban lakes have a significant slow-release regulating effect on urban heat island.Because of people's hydrophilicity that makes the lakeside has become the most attractive urban space in the city,and the urban lakeside space has been in a state of being forced to over-exploit.This research focuses on the lake water bodies in the high-density built-up area of the city,taking Meixi Lake in Changsha as the research object,through parallel fixed-point observation and CFD(computer fluid dynamics)numerical simulation and other technologies,the characteristics of the thermal environment around the lake in the high-density built-up area are analyzed.Mathematical statistical analysis reveals the changing law of the slow-release effect of urban lakes in high-density built-up areas in summer,and further analyzes the slow-release adjustment differences of lake water bodies on the thermal environment of high-density built-up areas through scenario simulations.The main research work and conclusions of this study are as follows:(1)Review of the research progress on climate regulation of urban water bodies.The first chapter of this research summarizes the research progress of urban water bodies,including the main research content and main research technology.At the same time,the research ideas and technical routes are put forward through the review and summary of the existing research.(2)Field measurement research on the slow-release effect of lakes in high-density built-up areas.The third chapter of this research used the long-term fixed-point tracking observation of the surrounding environmental temperature of Meixi Lake to effectively characterize the lake's influence on the surrounding environment and climate.The study showed that the lake has an obvious thermal slow-release regulation effect on the surrounding environment,and the law of spatial change obvious.The slow-release effect of the lake on the downwind area is stronger than that in the upwind and vertical directions,and the thermal slow-release intensity of the lake decreases by 0.43? for each 150m retreat from the lake.(3)Research on the factors affecting the slow-release effect of lakes in high-density built-up areas.The third chapter of this study conducted a detailed correlation analysis of the thermal environment characteristics around the lake from the four major aspects of distance,spatial form,underlying surface,and meteorological elements.The study showed that the surrounding environmental factors of high-density built-up areas have a relationship with the slow-release efficiency of water bodies.Among them,the distance to the lake,the average distance to the building,and the relative humidity have a strong ability to explain the temperature changes around the lake.(4)CFD interactive verification of lake thermal slow-release effect in high-density built-up areas.In Chapter 4 of this study,the CFD simulation and feasibility verification of actual calculation examples show that the CFD model used in this paper can qualitatively reproduce the intensity and range of the slow-release effect of lakes in high-density built-up areas,and the cooling effect of lakes within a range of 550m downwind.Obviously,the CFD scenario simulation method can be effectively used as an evaluation tool to determine the cooling potential of lake water bodies in an urban environment.(5)Scenario simulation study of lake thermal release effects in high-density built-up areas.The fourth chapter of this study uses CFD scenario simulation to simulate and analyze 3 different types and 10 different scenarios under the change of lake factors,building factors,and meteorological factors.As the surrounding area of Meixi Lake was "enclosed" by the high-intensity construction area,the air circulation between the water body and the surrounding area was blocked,and the slow-release effect of the water body was not fully demonstrated.Studies have shown that increasing the building retreat distance,reducing the degree of lakeshore enclosure,and reducing the height of lakeside buildings can all improve the ventilation capacity of the lakeside area and optimize the thermal release effect of the lake.Reducing the building height(cooling rate of 1.73?)and reducing the degree of enclosure of buildings around the lake(cooling rate of 1.86?)has a greater positive impact on the lake's thermal release than the building's retreat distance(cooling rate of 1.36?).At the same time,based on the above analysis conclusions and related research results,this study puts forward a corresponding optimization strategy for the thermal release effect of lakes in high-density built-up areas.This research can deepen the understanding of the slow-release effect of lake water in high-density built-up areas,and help urban planners and landscape designers to design urban lake-waterfront space from the perspective of overall thermal environment perception,improve local microclimate,and maintain the sustainable development of urban ecosystem.