Is­rael’s largest wind tun­nel

New fa­cil­ity serves as a platform for con­duct­ing a va­ri­ety of en­vi­ron­men­tal ex­per­i­ments, with­out ever leav­ing the lab­o­ra­tory

The Jerusalem Post - The Jerusalem Post Magazine - - CONTENTS - • By MAYA PELACH/ZAVIT

It can af­fect planes in flight and ships at sea, ac­cel­er­ate the spread of wild­fires, cause road clo­sures and even lead to loss of lives. It’s the wind, and while we may not al­ways pay at­ten­tion to it, it can de­ter­mine our fate at a mo­ment’s no­tice. The wind is a seem­ingly sim­ple thing – a mo­tion of air “par­ti­cles” flow­ing in a cer­tain di­rec­tion – but it is in­flu­enced by sev­eral en­vi­ron­men­tal con­di­tions that make it un­pre­dictably dif­fi­cult to fore­see it or its out­come. This is what led a team of re­searchers at the Is­rael In­sti­tute for Bi­o­log­i­cal Re­search in Ness Ziona in 2015 to de­velop the first and only en­vi­ron­men­tal wind tun­nel in Is­rael ca­pa­ble of mim­ick­ing the wind flow in the lower at­mos­phere. This is where ex­per­i­ments in­volv­ing the ef­fect the wind has on vary­ing as­pects of our lives are car­ried out.

Ad­vanc­ing sci­ence one gust of wind at a time

“The en­vi­ron­men­tal wind tun­nel is a sort of ‘at­mo­spheric lab’ that al­lows us to mimic me­te­o­ro­log­i­cal con­di­tions and ex­treme weather sit­u­a­tions that ex­ist in na­ture,” ex­plains Dr. Yar­dena Bo­hbot-Ra­viv, head of the En­vi­ron­men­tal Wind Tun­nel Lab­o­ra­tory. “The tun­nel in ef­fect al­lows us to mimic and con­trol wind char­ac­ter­is­tics, but not only that – it also lets us recre­ate the ex­act same con­di­tions again and again, which al­lows us to per­form a myr­iad of ex­per­i­ments un­der con­trolled con­di­tions. This en­ables us to achieve sta­tis­ti­cal re­sults that are much more pre­cise than would be ob­tained in a field ex­per­i­ment where weather con­di­tions are con­stantly chang­ing.”

Wind tun­nels are used as tools for per­form­ing a wide range of ex­per­i­ments meant to ex­am­ine the ef­fect the wind has in var­i­ous sit­u­a­tions. For in­stance, wind tun­nels serve as tools for study­ing the dis­per­sion of var­i­ous air pol­lu­tants, such as gas emis­sions from smoke­stacks and cars; for as­sess­ing risk of emis­sions of dan­ger­ous sub­stances in pub­lic spa­ces; for ex­am­in­ing the ef­fect of nat­u­ral phe­nom­ena such as snow or ero­sion; and they can also as­sist in ed­u­cated ur­ban plan­ning.

The tun­nel con­structed at the Is­rael In­sti­tute for Bi­o­log­i­cal Re­search spans three floors in a des­ig­nated build­ing, which makes it the largest wind tun­nel in Is­rael. The tun­nel it­self oc­cu­pies one level of the build­ing and con­sists of a metal “sleeve” 14 me­ters long, through which the wind is pow­ered ac­cord­ing to the strength, hu­mid­ity and tem­per­a­ture de­sired in each ex­per­i­ment. How­ever, this just serves as the “stage” of this com­pli­cated de­vice. Be­hind the scenes is a huge S-shaped sys­tem to­tal­ing 32 me­ters in length, span­ning the re­main­ing floors of the build­ing, where the wind is gen­er­ated ac­cord­ing to de­sired spec­i­fi­ca­tions.

The end of the tun­nel leads to a large cell in which the re­searchers per­form var­i­ous tests and ex­per­i­ments us­ing unique equip­ment and tech­nol­ogy, most of which does not ex­ist in any other tun­nels in Is­rael. Ac­cord­ing to Ra­viv, “There are just a hand­ful of tun­nels world­wide with sim­i­lar ca­pa­bil­i­ties. There is a sim­i­lar wind tun­nel at Ham­burg Univer­sity con­sid­ered to be among the largest of its kind in the world.

We re­lied on help from their ex­perts at var­i­ous stages of build­ing and con­struc­tion, and we con­tinue to col­lab­o­rate with them on var­i­ous ex­per­i­ments and re­fer to them for pro­fes­sional ad­vice.”

Im­me­di­ate im­pli­ca­tions on air pol­lu­tion re­duc­tion

Wind tun­nels are not a novel thing; they been around since the 1970s. A wide range of wind tun­nels can be found around the world, each de­signed and equipped ac­cord­ing to their in­tended pur­poses. They dif­fer from each other mainly by size and the wind power that blows through them.

“In the ’70s, this was an ex­cit­ing new tech­nol­ogy and it be­came stan­dard prac­tice to test ev­ery­thing in a wind tun­nel,” ex­plains Ra­viv. “In the ’80s, as com­put­ers were be­com­ing more widely used, there was a grad­ual shift to use of com­put­er­ized mod­els. How­ever, as time went by, it be­came ap­par­ent that com­put­er­ized mod­els can­not take into ac­count the con­stant fluc­tu­a­tion in en­vi­ron­men­tal con­di­tions. In field ex­per­i­ments, we are con­fined to real-time con­di­tions that do in­deed vary con­tin­u­ously. There­fore, wind tun­nels are again be­com­ing pop­u­lar. As tech­nol­ogy im­proves, we can use them to test more and more things, as well as use them to aid in im­prov­ing and ver­i­fy­ing com­put­er­ized mod­els. These three ap­proaches to test­ing – field tests, com­put­er­ized mod­els and wind tun­nels – com­ple­ment each other in ob­tain­ing a fore­cast that would oth­er­wise be dif­fi­cult and of­ten im­pos­si­ble to ob­tain.”

In the wind tun­nel at the Is­rael In­sti­tute for Bi­o­log­i­cal Re­search, they know for in­stance, how to test for the most ef­fec­tive way to lay out wind turbines. 3-D mod­els that mimic the earth’s sur­face are placed in the ex­per­i­men­tal cell at the end of the tun­nel, and small wind turbines through which wind is pow­ered are then placed on these. By lay­ing the turbines out in var­i­ous con­fig­u­ra­tions and un­der vary­ing wind con­di­tions, they can as­sess which con­fig­u­ra­tion uti­lizes wind power most ef­fi­ciently rel­a­tive to the unique land­scape on which the turbines will be de­ployed. In a coun­try such as Is­rael, where the is­sue of set­ting up wind turbines has al­ways been con­tro­ver­sial, prior knowl­edge that can be ob­tained in the tun­nel is of great value.

An ex­per­i­ment cur­rently be­ing car­ried out in the tun­nel in­volves the dis­per­sion of pol­lu­tants in an ur­ban en­vi­ron­ment. Ra­viv ex­plains, “Ac­cept­able com­put­er­ized mod­els for the dis­per­sion of pol­lu­tants in the at­mos­phere are in­suf­fi­cient in ur­ban en­vi­ron­ments, be­cause of the com­plex­ity of the wind flow around build­ings and veg­e­ta­tion. An in­no­va­tive study cur­rently be­ing con­ducted in the tun­nel aims to im­prove the mod­els for the dis­per­sion of pol­lu­tants in pop­u­lated ur­ban en­vi­ron­ments. This project is tak­ing place in col­lab­o­ra­tion with the Tur­bu­lence Struc­ture Lab­o­ra­tory at Tel Aviv Univer­sity, and its goal is to pro­vide a re­al­is­tic model of pol­lu­tant dis­per­sion in the city that will have im­me­di­ate im­pli­ca­tions on air pol­lu­tion re­duc­tion in cities.”

In ad­di­tion, a model is cur­rently be­ing de­vel­oped in the wind tun­nel at the Is­rael In­sti­tute for Bi­o­log­i­cal Re­search, for as­sess­ing wind com­fort around build­ings, in­clud­ing tall build­ings in Is­raeli cities. It is es­ti­mated that by the year 2030, 60% of the world’s pop­u­la­tion will be liv­ing in cities. This es­ti­mate bears im­pli­ca­tions on qual­ity of life that de­mand prior prepa­ra­tion, es­pe­cially in a densely pop­u­lated coun­try such as Is­rael. The model be­ing de­vel­oped in the tun­nel is based on build­ing a scaled-down ur­ban land­scape and in­cor­po­rat­ing me­te­o­ro­log­i­cal data in or­der to de­tect ex­treme sit­u­a­tions and ex­am­ine en­gi­neer­ing so­lu­tions for po­ten­tial wind dis­com­fort in ur­ban plan­ning. Prof. Sh­muel Shapira, CEO of the Is­rael In­sti­tute for Bi­o­log­i­cal Re­search states, “In terms of safety, en­vi­ron­ment and more, our as­sump­tion is that build­ings with more than 10 floors as well as pub­lic build­ings should get ap­proval in the en­vi­ron­men­tal wind tun­nel.”

Epi­cen­ter of knowl­edge like no other

One of the qual­i­ties that cause the tun­nel to stand out is its ex­treme flex­i­bil­ity, which al­lows a very wide range of ex­per­i­ments to be car­ried out. The tun­nel is equipped with a num­ber of vary­ing ad­vanced laser-based tech­nolo­gies for mea­sur­ing wind. The laser sen­sor is lo­cated in the ex­per­i­men­tal cell and col­lects real-time data of the wind power at var­i­ous points that are de­cided upon by the re­searchers car­ry­ing out the ex­per­i­ment. The data is trans­ferred from the sen­sors to a com­puter and is then pro­cessed by the lab re­searchers.

“The sys­tem al­lows vi­su­al­iza­tion of wind flow at a very high spa­tial res­o­lu­tion (about one mil­lime­ter),” ex­plains Dr. Eyal Fa­tal, head of the math­e­mat­ics depart­ment at the Is­rael In­sti­tute for Bi­o­log­i­cal Re­search. “This is a pas­sive mea­sur­ing sys­tem that doesn’t in­ter­fere with wind flow and thus pro­vides more re­li­able mea­sure­ments.”

In par­al­lel to these sys­tems, re­searchers at the in­sti­tute are also spe­cial­iz­ing in mea­sur­ing con­cen­tra­tions of gases.

“This is a sys­tem that has been tai­lored to un­dergo ex­per­i­ments in the wind tun­nel at the in­sti­tute and serves as a tool for mea­sur­ing gas emis­sions from pis­tons of mo­tor ve­hi­cles,” ex­plains Fa­tal. “There is no other de­vice like it in Is­rael. Each sys­tem and de­vice con­trib­utes unique data that, when taken to­gether, al­lows us to con­struct a mul­ti­di­men­sional im­age of wind flow and pro­vides us with rel­a­tively spe­cific an­swers to ques­tions that we would oth­er­wise have no means of ob­tain­ing an­swers to.”

The wind tun­nel holds the po­ten­tial for tremen­dous re­search growth, in the­o­ret­i­cal sci­ence as well as in ap­pli­ca­tion in the field, both of which are seen by ev­ery in­dus­tri­al­ized coun­try as step­ping stones to­ward fi­nan­cial growth.

“Since this is cur­rently the only tun­nel of its kind in Is­rael with only a hand­ful like it in the world, we ad­vise uni­ver­si­ties, re­search in­sti­tu­tions, and pri­vate com­pa­nies to make use of the tun­nel to per­form ex­per­i­ments that meet their spe­cific needs,” says Shapira.

“The idea is to test ap­pli­ca­tions that can­not al­ways be tested us­ing stan­dard field ex­per­i­ments and/ or com­put­er­ized mod­els or to ob­tain more re­li­able re­sults. Our goal is to use the tun­nel in or­der to en­cour­age sev­eral facets of en­vi­ron­men­tal re­search, in­clud­ing safety and ur­ban plan­ning, as well as to pro­vide a platform for the devel­op­ment of var­i­ous new re­search fields in Is­rael and abroad.”

(Pho­tos: Is­rael In­sti­tute for Bi­o­log­i­cal Re­search)

THE EN­VI­RON­MEN­TAL wind tun­nel de­vel­oped at the Is­rael In­sti­tute for Bi­o­log­i­cal Re­search.

ED­U­CATED UR­BAN plan­ning: Such tun­nels can serve as tools for study­ing the dis­per­sion of var­i­ous air pol­lu­tants.

THE TUN­NEL acts as a sort of ‘at­mo­spheric lab’ that al­lows the lab­o­ra­tory to mimic me­te­o­ro­log­i­cal con­di­tions and ex­treme weather sit­u­a­tions that ex­ist in na­ture.

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