Numerical Simulation on Wind Flow over Step-shaped Cliff Topography with Rough Surface

Transcription

1 In. J. Envron. Res., 7(1): , Wner 013 ISSN: Nmercal Smlaon on Wnd Flow over Sep-shaped Clff Topography wh Rogh Srface Yassn, M.F. 1,* and Al-Harb, M. 1 1 Deparmen of Envronmenal Technology Managemen, wa Unversy, wa Facly of Engneerng, Ass Unversy, Egyp Receved 0 Aprl 01; Revsed 4 Ag. 01; Acceped 17 Ag. 01 ABSTRACT:To enhance he ndersandng of he mpac of obsacle bldngs on pollon ransporaon and dsperson n he amospherc bondary layer, s necessary o know he amospherc flow characerscs over errans. Wnd flow characerscs n a bondary layer over a sep-shaped clff opography model wh rogh and smooh srfaces were sded nmercally sng Compaonal Fld Dynamcs models (CFD). The CFD models ha were sed for he smlaon were based on he seady-sae Reynolds-Average Naver- Soke eqaons (RANS) wh rblence models; sandard and RNG models. The rogh srface was modeled sng wndbreak fence, whch was se on he sep-shaped clff model srface. The resls of he nmercal model were valdaed agans he wnd nnel resls n order o opmze he rblence model. Nmercal predcons agreed reasonably wh he wnd nnel resls. The resls ndcaed ha rogh srface has a grea nflence on he rblen flow characerscs and vore roang. The wnd velocy for rogh srface near he grond level was observed o be lower han ha for he smooh srface of he sep-shaped clff model. Large flow separaons were formed by he wndbreak fences. Dsoron of he flow a he wndward corner of he sep creaed a seep graden of velocy and large rblen mng. ey words: Amospherc rblence,cfd models, Rogh srface,terran model,wnd flow INTRODUCTION Wnd flow above comple erran has become one of he mos mporan opcs of envronmenal research. Ths s becase wnd rbnes are ncreasngly ereced n areas wh comple orography, frherng he corse of wnd energy s he man mpes for he nvesgaon. Good knowledge of he flow over comple erran s essenal for precsely esmang wnd energy poenal, assessng srcral loads on rbnes. An ndersandng of flow n comple erran s also crcal for he parameerzaon of form drag n meeorologcal models. I s also sgnfcan for varos dsperson applcaons. Several sdes have pad a grea deal of aenon o amospherc bondary layer flow over hlls. Jackson and Hn (1975) presened her wodmensonal (D) analyss of rblen flow n comple erran, whch was laer eended o hree-dmensonal (3D) flow by Mason and Sykes (1979). Ths heory has been refned and mplemened nmercally no commercal codes sch as MS3DJH, MSFD and WAsP (Taylor e al. 1983; Walmsley e al. 1986; and Belaars e al. 1987). These so-called lnear models have he advanage of prodcng compaonally fas and *Correspondng ahor E-mal: mohamed_f_yassn@homal.com 173 accrae resls for errans of genle slopes of less han 0.3 or 17æ% (Wood 1995; Walmsley and Taylor 1996).Unl recenly, many nvesgaors have aemped o measre rblence n he backwardfacng sep flow wh sophscaed epermenal echnqes (Eaon and Johnson, 1981). However, here are relavely fewer sdes on wnd flow over sepshaped opography wh rblen bondary layer (Bowen and Lndley, 1977; Adams and Johnson, 1988; Fredrch and Arnal, 1990; Dlal and Garshora, 1991; asag and Masnaga, 1993; Olsson, 1999). Wllam and Joseph (000) evalaed he vably of sng a sep-shaped erran represenaon of a smooh monan profle n model smlaons of smallamplde monan waves, where he resl can be compared agans known analyc solons. Ross e al. (004) have performed nmercal and epermenal sdes n order o assess he performance of dfferen rblence closre schemes n predcng he flow feld over a hll. Two-dmensonal seep hlls of dfferen slopes, n boh neral and sably srafed flow condons were sded. Lorero and Frere (005) have nvesgaed he effecs ha a large change n

2 Yassn, M.F. and Al-Harb, M. srface elevaon provokes on he properes of he amospherc sng wnd nnel and waer channel epermens. Mozaks and Bergels (005) presen predcons of he wo-dmensonal rblen flow over a ranglar rdge. Trblen bondary layer wh a sep change n srface roghness was nvesgaed epermenally by rogsad and Nckels (006). Pogga e al. (007) colleced a new daa se above a erran of genle hlls o eplore epermenally and heorecally he -D srcre of he mean velocy. Blocken e al. (007) addressed he problem of horzonal homogeney assocaed wh he se of sand-gran roghness wall fncons. Ths s done by focsng on he CFD smlaon of a nerally srafed, horzonally homogeneos amospherc bondary layer flow over nformly rogh, fla erran. Ths paper presens he resls of nmercal nvesgaaon for sdyng he effec of he rogh srface on he wnd flow n he rblen bondary layer over sep-shaped clff opography. Therefore, he am of he presen work s o mprove he ndersandng of mechansm of smlaon on he wnd flow over erran opography and o predc he wnd flow over local opography. For hs prpose, a wo-dmensonal model of sep-shaped clff wh and who obsacles fence was consdered. Mean velocy, rblence nensy and rblen knec energy were analyzed and dscssed a dfferen locaons n he downwnd dsance over sep-shaped clff model nder neral amospherc condons. MATERIALS & METHODS In hs paper, he nmercal smlaons were performed sng he FLUENT CFD code (Flen, 009), whch s based on he fne volme mehod o solve he eqaons of conservaon for he dfferen ranspored qanes n he amospherc flow (mass, momenm and energy). The code frs performs he copled resolon of he pressre and velocy felds and hen evolon of oher parameers. A wo-dmensonal sep-shaped clff confgraon was chosen as a model of seep crvare obsacles. The model geomery s shown n Fg. 1. In hs fgre, Z means he hegh from he pper srface of he sepshaped clff. The sep-shaped clff model s modeled on a 1:1000 scale. The geomery chosen was dencal o ha eamned epermenally n a wnd nnel sdy ( ) = 1 ρ by Yassn e al. (001), where he clff hegh was 75 m hgh n he real scale and s lengh was 0H (H=75 mm). The smlaed rogh srface was modeled wh wndbreak fence and he smlaed smooh srface modeled who wndbreak fence. The wndbreak fence was se on he sep-shaped clff model srface. The compaonal doman was 3 m long 1.8 m hgh, whch was dscresed as grds. The model edge dsance 7H from he nle doman, 13.33H from he ole doman, and 9.33H from he pper doman. Eensve ess of he grd nervals are carred o wh ncreasng grd nerval nl frher refnemen s shown o be less sgnfcan. The compaonal mesh employed was a convenonal non-nform mesh, for whch he opmal mesh was denfed, conssng of cells of average sde szes. The orgn of he doman was defned a he cener of he fron edge of he sep-shaped clff model. The epanson rao n he non-nform grd was 1.1. The grd nervals near he obsacles n he -, and z-drecons are =0.16H, and z = 0.1H respecvely. Fne cells were defned over he sep-shaped clff model, where hgh gradens were epeced, and coarse cells elsewhere. A mesh refnemen es was performed o denfy he opmal mesh resolon and ensre he resls were meshndependen. To mnmze rncaon error, cell-sze ncremens were gradal and lmed o a mamm ncremen of 5% beween congos cells. In Flen, The grd was generaed sng GAMBIT sofware. The compaonal grd confgraons over he sepshaped clff model wh and who obsacle fence are shown n Fg.. The FLUENT CFD package has been confgred o solve he Naver Sokes eqaons for he flow over he sep-shaped clff sng he sandard k- rblence model (Lander and Spaldng, 1974) and RNG k- rblence model (Yakho e al., 199) for compaonal effcency and accracy. The RNG k- model dffers from he sandard k- rblence scheme only hrogh he modfcaon o he eqaon for, whch ncldes an addonal snk erm n he rblence dsspaon eqaon o accon for non-eqlbrm sran raes and employs dfferen vales for he model coeffcens (m and Bak, 004). The governng eqaons of he model are shown below Conny eqaon = 0 (1) Momenm eqaon p ν () 174

3 In. J. Envron. Res., 7(1): , Wner Smooh srface Rogh srface Fg.. he compaonal sep-clff confgraon Z Uα Z Z H X X/H=0 U H Z =0 Fg. 1. Two-dmensonal sep-clff model T ke - ranspor eqaon ν σ ν = k (3) - ranspor eqaon for sandard k- rblence model c c 1 ν σ ν = (4) - ranspor eqaon for RNG k- rblence model R c c ls = ν σ ν (5) ) (1 / β η η η µη = k c R (6) 1/ = η (7) δ ν 3 = (8) ν µ = c (9)

4 Nmercal Smlaon on Wnd Flow where, s he h mean velocy componen; p s he devaon of pressre from s reference vale and ρ s he ar densy. ν s he rblen vscoses of momenm, respecvely, δ s he kronecker dela. ν s he knemac vscosy of ar. η =4.38 and β 0 = Table 1 show he consan vales n he ranspor eqaons. In modelng amospherc flow, smaller grd sze s desrable near he srface of he sep-shaped clff model o beer resolve flow, b away from he model, a larger grd sze s allowable. The governng eqaons se was solved nmercally on a saggered grd sysem sng he fne-volme followng he sem-implc Mehod for pressre-lnked Eqaon (SIMPLE) algorhm descrbed by Paankar (1980). The sandard and RNG k- rblence models were employed here for comparson becase of s wdespread accepance n dverse felds. Velocy nle bondary layer condons were sed n he man nle wnd flow. The nal wnd speed s nform (10 m/s) wh low rblence nensy. A serdefned sbrone for ncldng he rblence he power law n rral area nle velocy profle no FLUENT code was developed and sed n he analyss. The nal condon for wnd veloces, rblen knec energy, and s dsspaon rae are specfed as (FLUENT, 009) U = U H Z Z µ H n (11) τ = (1) 3/ 4 c 3/ cµ ( Te ) = (13) l where, U H s he velocy a a hegh Z H ; Z s he hegh above he grond, and n s he power eponen, τ s he frcon velocy and l s he rblence lengh scale. The grond and sep-shaped clff srfaces are defned as walls wh no-slp bondary condon. The wall bondary condons for momenm are appled o all sold srface and rogh walls. Zero graden bondary condons are appled a he oflow and pper bondares. The epermenal daa was sed for he valdaon of nmercal smlaon obaned from a dealed wnd nnel sdy by Yassn e al. (001). Epermens were performed n a closed-crcle bondary layer wnd nnel, whch s shown n Fg.3. The wdh and hegh of he es secon were. and 1.5 m. A neral srafed amospherc bondary layer was smlaed sng hree spres, one 90 mm hgh cbc array placed s downsream of he conracon e and followed by 60 and 30 mm cbc roghness elemen, coverng 10. m of he es-secon floor. Ths arrangemen was employed o generae a hck rblen bondary layer as he approachng flow. Reynolds nmber based on U H and H s Fg. 4 shows he smlaed rblen bondary layer profle a X=0.0 corresponds o he cener of he sep model. Trppng wres (1 mm recanglar colmns, 50 mm nervals) were arranged over he sep-shaped clff. The wndbreak fence over he sep-shaped clff was a sold plae fence, and was posoned a nervals of 50 mm, he same as for he rppng wres. Wnd velocy was measred sng a ho wre Consan Temperare Anemomeer (CTA) sysem wh a spl fber probe, whch was 70 µm dameer and 1.5 mm long. Ths was becase he X-wre probe anemomeers for rblence measremen canno gve reasonable accracy when he rblence nensy s larger han 0.3 (Ishhara, 1999). Wnd velocy measremens over he sep-shaped model were made wh spl-fber probe (55R55) n conncon wh a 90N10 DANTEC consan emperare anemomeer sysem. The mean velocy was normalzed by he reference velocy, U H whch s he velocy of he sepshaped clff hegh. The velocy profles were measred a he posons over he sep-shaped clff srface shown n Fg. 5. To clarfy he change n he flow characerscs, he smlaed daa were nerpolaed a he same grd pons as n he wnd nnel epermen. Smoke flow vsalzaon was done n he wnd nnel o see wha knd of flow characerscs appeared arond he wndward corner and over he sep-shaped clff model. The nmercal resls of he wnd nnel epermens for he flow srcre were compared sng he flow vsalzaon and sreamlnes arond he wndward corner and over he sep-shaped clff model, as s shown n Fg 6. On he wndward corner of he sep-shaped clff, he flow separaon was creaed. A reaachmen pon appeared over he sep-shaped clff and moved downsream owards he downwnd sree. The nmercal smlaon of he wnd flow was herefore conssen and n agreemen wh he measremens sed n wnd nnel epermens.the smlaed daa was nerpolaed a he same grd pons as n he wnd nnel epermen. The nmercal daa of he sandard and RNG k- rblence models was valdaed agans he daa obaned from he wnd nnel epermens a varos locaons. Fgs. 7-8 show he vercal profles of he normalzed horzonal velocy for he srfaces wh and who 176

5 In. J. Envron. Res., 7(1): , Wner 013 Table 1. Consans n he rblence models Models c µ c 1 c σ k σ sandard κ- model RNG κ- model mm Wnd Spres Spl - Fber probe Z Y Sep-clff model X Roghness Roghness Roghness mm mm mm H=75mm 1450 mm 6550 mm 15 mm 156 mm 1015 mm Fg. 3. Schemac dagram of he wnd nnel epermenal Z, mm Trblence nensy m/s 100 Mean velocy Fg. 4. Vercal dsrbon of mean velocy and rblence nensy of ncden flow (a X= -800 mm & Y=0) obsacles fence a X/H=-5, -1, 0.5, 3.8, 7.8 and A good agreemen beween he rblence models and he wnd nnel epermen was observed for boh he srfaces who and wh obsacles fence. A slgh dfference beween he rblence models and he wnd nnel epermens for he srface who obsacles fence was observed a X/H=-5, 7.8 and 11.8 and for he srface wh obsacles fence a X/H=-5, and 0.5, whch cold have been de o he se of hree-dmensonal solaed sep-shaped clff n he wnd nnel epermen. However, he sandard rblence model was showed o be generally close o he wnd nnel epermens for he srface who obsacles fence. RESULTS & DISCUSSIONS The dsrbons, vecors, and sreamlnes of he horzonal velocy over he sep-shaped clff model for he rogh and smooh srfaces are shown n Fgs Fg.1 shows he vercal profles of he mean horzonal velocy over he sep-shaped clff model for he rogh and smooh srfaces who a varos locaons; X/H=-5, -1, 0.5, 3.8, 7.8 and These fgres show ha he sandard and RNG rblence model predc smlar wnd veloces over he sep-shaped clff model, ecep for he smooh srface a 1<Z/H<1.75. The mos nensve movemen 177

6 Yassn, M.F. and Al-Harb, M. Fg. 5. Skech of he dfferen locaons for he vercal profles on sep-clff model Sandard k- model SRNG k- model Wnd nnel epermen Fg. 6. Flow vsalzaon and sreamlnes arond he fronal corner of he sep-clff model 178

7 In. J. Envron. Res., 7(1): , Wner 013 Fg. 7.Vercal profles of normalzed horzonal velocy over sep-clff model who wndbreak fence a dfferen locaons X/H Fg. 8. Vercal profles of normalzed horzonal velocy over sep-clff model wh wndbreak fence a dfferen locaons X/H 179

8 Nmercal Smlaon on Wnd Flow m/s Sandard k- model Who wndbreak fence m/s RNG k- model Who wndbreak fence m/s Sandard k- model Wh wndbreak fence m/s RNG k- model Wh wndbreak fence Fg. 9. Mean horzonal velocy dsrbons over he sep-clff model Sandard k- model Who wndbreak fence RNG k- model Who wndbreak fence Sandard k- model Wh wndbreak fence RNG k- model Wh wndbreak fence Fg. 10. Mean horzonal velocy vecors over he sep-clff model 180

9 In. J. Envron. Res., 7(1): , Wner 013 Fg. 11. Sreamlnes of he mean horzonal velocy over he sep-clff model Fg. 1. Vercal profles of normalzed horzonal velocy over sep-clff model a dfferen locaons 181

10 Yassn, M.F. and Al-Harb, M. of he flow appeared near he wndward corner of he sep-shaped clff. The mean horzonal velocy appeared o be very small a he wndward corner of he sep-shaped clff. The vore appeared o be roang clockwse on he sep-shaped clff rogh srface beween every wndbreak fences and for he smooh srface near he grond wndward of he sepshaped clff. The vore was generaed by sandard rblence model was observed smaller han ha by RNG rblence model. A negave velocy was fond for he srface wh obsacles fence. Ths mean ha he ar movemen assocaed wh he vore-lke moon effecvely owards boh he leeward and wndward of he wndbreak fences n he sep-shaped clff. The wnd velocy adacen for he smooh srface was hgher han ha for he rogh srface of he sepshaped clff. Flow separaon a he wndward corner of he sep-shaped clff for he smooh srface was qe small f presen a all, and compared o he rogh srfaces. Relavely large flow separaons were formed by he wndbreak fences. The dfference beween he smooh and rogh srfaces was relavely small a Z/ H>. A hck nernal bondary layer was generaed by he rogh srface. Inversely, nernal bondary layer for he smooh srface was very hn becase here was no wndbreak fence. Whle, a X/H= 0.5, he hck nernal bondary layer was generaed over he smooh srface compared o he oher de o he rblen mng, whch was formed by he dsoron of flow a he wndward corner of he sep-shaped clff. The mamm velocy was observed a X/H= 0.5 for he smooh and rogh srfaces. Ths was becase he wndward corner generaed he separaon flow. The prevos resls showed ha he rogh srface has a grea nflence on he flow characerscs and vore roang. Besdes he mean velocy, s of neres o know how rblence mgh be modfed as he flow goes over he sep-shaped clff model. Trblence srcres behnd wo-dmensonal hll are poorly ndersood.fgs show he conors of he rblence nensy over he sep-shaped clff model for he smooh and rogh srfaces. The vercal profles of he rblence nensy over he sep-shaped clff model for he smooh and rogh srfaces a varos locaons; X/ H=-5, -1, 0.5, 3.8, 7.8 and 11.8 are shown n Fg.14. Vgoros rblen mng was observed n he pper par of he fronal corner of he sep-shaped clff model. The rblence nensy over he rogh srface appeared o have smlar paerns a Z/H<. Whle, he rblence nensy over he smooh srface appeared o have smlar paerns on he sep-shaped clff srface a X/H=3.8, 7.8 and 11.8 for Z/H< respecvely. The rblence nensy vared slowly wh hegh. Over he sep-shaped clff, here was sgnfcan hgh nensy near he srface and hs led o a large ncrease n he rblen sress. There was a srong graden n he rblence nensy a X/H=0.5 wh he mamm magnde close o he sep-shaped clff srface. A regon of hgh-rblence nensy appeared o be along he shear layer downsream of he sep-shaped clff model. Peak vales of he rblence nensy creaed n he zones were characerzed by he hghes velocy gradens. The rblence nensy showed hgher vale a Z/H< over he sep-shaped clff for he smooh srface de o he seep graden of he velocy han ha of he rogh srface. The vale of he rblence nensy over he sep-shaped clff a X/H= 3.8, 7.8 and 11.8 for he rogh srface was larger han ha for he smooh srface. The rblen knec energy s one of he mos mporan varables n he amospherc bondary layer. Fgs show he conors and vercal profles of he rblen knec energy over he sep-shaped clff model for he smooh and rogh srface srfaces. I s showed ha an ncrease n wnd velocy sgnfcanly decreases he rblen knec energy over he sepshaped clff model. The dsrbon of he rblen knec energy qanfes he rblen dffson along he shear layer and s conssen wh he drecon of he mean flow. The rblen energy for he rogh and smooh srfaces had smlar paern a Z/H>. The peak vale of he rblen energy appeared o be near he wndward corner a X/H=0.5 for he srface who obsacles fence and was consdered o be closely relaed o he small separaon as descrbed above. The mnmm vale of he rblen energy for he srface who an obsacle fence was dsplayed a X/H=-5. The vales of rblen energy appeared o be slghly hgher a Z/H< for he rogh srface han ha for he smooh srface, ecep a X/H=0.5 de o he large velocy graden. CONCLUSION A wo-dmensonal compaonal fld dynamcs (CFD) model wh he sandard and RNG k- rblence models were sed o nvesgae he effecs of he smooh and rogh srfaces on he amospherc flow over wo-dmensonal sep-shaped clff model sng FLUENT code. The valdaon of he nmercal model was evalaed and agreed wh wnd nnel daa. The valdaon of he nmercal smlaon hrogh he wnd nnel epermen enhances he aspec ha nmercal smlaons, whch are a low-cos ool able o provde n reasonable me accrae resls regardng fld dynamcs problems. The crren sdy clearly ndcaes ha here s sgnfcan nflence of he smooh and 18

11 In. J. Envron. Res., 7(1): , Wner 013 Sandard k- model Who obsacle fence Sandard k- model Who obsacle fence Sandard k- model Wh obsacle fence Sandard k- model Wh obsacle fence Fg. 13. Trblence nensy dsrbons over he sep-clff model Fg. 14. Vercal profles of normalzed rblence nensy over sep-clff model a dfferen locaons 183

12 Nmercal Smlaon on Wnd Flow Sandard k- model Who obsacle fence RNG k- model Who obsacle fence Sandard k- model Wh obsacle fence RNG k- model Wh obsacle fence Fg. 15. Trblen knec energy, dsrbons over he sep-clff model Fg. 16. Vercal profles of normalzed rblen knec energy, over sep-clff model a dfferen locaons 184

13 In. J. Envron. Res., 7(1): , Wner 013 rogh srfaces on he wnd flow over he sep-shaped clff model, he followng conclsons can be made: (a) For mean velocy feld, he mos nensve movemen of he flow appeared near he wndward corner of he sep-shaped clff. The mean horzonal velocy appeared o be very small a he wndward corner of he sep-shaped clff. The vore appeared o be roang clockwse on he sep-shaped clff srface for he rogh srface beween every wndbreak fences and for he smooh srface near he grond wndward of he sep-shaped clff. Inverse flow was fond wh he rogh srface. The wnd velocy adacen o he smooh srface was hgher han ha of he rogh srface of he sep-shaped clff. A hck nernal bondary layer was generaed by he obsacles fence. (b) For rblen feld, vgoros rblen mng was observed n he pper par of he fronal corner of he sep-shaped clff model. The rblence nensy vared slowly wh hegh. A regon of hghrblence nensy appeared o be along he shear layer downsream of he sep-shaped clff srface. Peak vales of he rblence nensy creaed n he zones were characerzed by he hghes velocy gradens. The rblence nensy showed hgher vale a Z/H< n he sep-shaped clff for he smooh srface. An ncrease n wnd velocy sgnfcanly decreases he rblen knec energy over he sepshaped clff model. The dsrbon of he rblen knec energy qanfes he rblen dffson along he shear layer and s conssen wh he drecon of he mean flow. The peak vale of he rblen energy appeared o be near he wndward corner a X/H=0.5 for he smooh srface. The mnmm vale of he rblen energy for he smooh srface was dsplayed a X/H=-5. REFERENCES Adams, E. W. and Johnson, J. P. (1988). Effecs of he Separang Shear Layer on he Reaachmen Flow Srcre. Ep. Flds, 6, Belaars, A., Walmsley, J. and Taylor, P. (1987). A med specral fne dfference model for nerally srafed bondary layer flow over roghness changes and opography. Bondary-Layer Meeorol., 38, Blocken, B., Sahopolos, T. and Carmele, J. (007). CFD smlaon of he amospherc bondary layer: wall fncon problems. Amospherc Envronmen 41, Bowen, A. J., and Lndley, D. (1977). A Wnd Tnnel Invesgaon of he Wnd Speed and Trblence Characerscs Close o he Grond over Varos Escarpmen shapes. Bondary Layer Meeorology, 1, Dlal, N. and Garshora, I. S. (1991). Trblen Flow arond a Blff Recanglar Plae. Par 1: Epermenal Invesgaonal. J. of Fld Engneerng, Trans. of ASME, 113 (3), Eaon, J.. and Johnson, J. P. (1981). A Revew of Research on Sbsonc Trblen Flow Reaachmen. AIAA Jornal, 19 (9), FLUENT Inc. (010). FLUENT ser Manal. Fredrch, R. and Arnal, M. (1990). Analyzng rblen backward-facng seep flow wh lowpass-flered naversokes eqaons. Jornal of Wnd Engneerng and Indsral Aerodynamcs, 35, Ishhara, T., Hb,. and Okawa, S. (1999). A wnd nnel sdy of rblen flow over a hree-dmensonal seep hll. J. of Wnd Eng. and Inds. Aerodyn., 83, Jackson, P, and Hn, J. (1975). Trblen wnd flow over a low hll. Q J Roy Meeorol Soc., 101, asag, N. and Masnaga, A. (1993). Trblence measremen n a separaed and reaachng flow over a backward-facng sep wh he ad of hree-dmensonal parcle rackng velocmery. Jornal of Wnd Engneerng and Indsral Aerodynamcs, 46, rogsad, P. A. and Nckels, T. B. (006). Trblen bondary layer wh a sep change n srface roghness. 13h Inernaonal Conference on Fld Flow Technologes, 6-9 Sepember 006, Bdapes, Hngary. Lander, B. E. and Spaldng, D. E. (1974). The nmercal compaon of rblen flows. Comp. Meh. Appl. Mech. Eng., 3, Lorero, J. B. R. and Slva Frere A. P. (005). Epermenal Invesgaon of Trblen Bondary Layers over Seep Two-dmensonal Elevaons. J. of he Braz. Soc. of Mech. Sc. & Eng., 7 (4), Mason, P. and Sykes, R. (1979). Flow over an solaed hll of moderae slope. Q J Roy Meeorol Soc., 105, Olsson, L. (1999). Seps owards an envronmenally ssanable ranspor sysem. The Scence of he Toal Envronmen, 35, Paankar, S. V. (1980). Nmercal hea ransfer and fld flow. McGraw-Hll. Pogga, D. alb, G., Albersonc, J. D and Rdolfd, L. (007). An epermenal nvesgaon of rblen flows over a hlly srface. Physcs of Flds, 19 (3), Ross, A. N., Arnold, S., Vosper, S. B., Mobbs, S. D., Non, N. and Robns, A. G. (004). A comparson of wnd-nnel epermens and nmercal smlaons of neral and srafed flow over a hll. Bondary Layer Meeorology, 113, Taylor, P.A., Walmsley, J. and Salmon, J. (1983). A smple model of nerally sraûed bondary-layer ûow over real erran ncorporang wave nmber-dependen scalng. Bondary-Layer Meeorol., 6,

14 Yassn, M.F. and Al-Harb, M. Walmsley, J. and Taylor, P. (1996). Bondary-layer flow over opography: mpacs of he Askerven sdy. Bondary Layer Meeorol., 78, Walmsley, J., Taylor, P. and eh, T. (1986). A smple model of nerally srafed bondary layer flow over comple erran wh srface roghness modlaons. Bondary Layer Meeorol., 36, Wllam, A. G. and Joseph, B.. (000). Behavor of flow over sep opography, Amercan Meeorologcal Socey. Aprl, Wood, N. (1995). The onse of separaon n neral, rblen flow over hlls. Bondary Layer Meeorol., 76, Yassn, M. F., ao, S., Ooka, R., Mrakam, S., Takahash, T. and Ohs, T. (001). Wnd nnel sdy on predcon of wnd characersc over local opography for sable se of wnd power saon (par 3): rblen characerscs of flow over a wo dmensonal sep model. Smmares of echncal papers of annal meeng, AIJ. 186