<HTML dir=ltr><HEAD> <META http-equiv=Content-Type content="text/html; charset=unicode"> <META content="MSHTML 6.00.6000.16915" name=GENERATOR></HEAD> <BODY> <DIV id=idOWAReplyText79446 dir=ltr> <DIV dir=ltr> <DIV> Dear all, I built up two identical airflow network models with one internal node and two boundary nodes. The only difference between them is that one is located in the ground level (say node height=2m when the floor height is 4m) while the other one is in the 10th level with node height of 38m. The flow connection is located at the same height of nodes. The results show that the pressure at nodes with huge difference. The node pressure is around -20 pa when the model is located in the ground floor; while it is -440 pa in the 10th floor.  If Pi is the surface pressure due to wind, as suggested by Hensen (1991), it should equal to <SPAN lang=EN-US style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri','sans-serif'; mso-bidi-font-size: 11.0pt; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 新細明體; mso-fareast-theme-font: minor-fareast; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; mso-ansi-language: EN-US; mso-fareast-language: ZH-TW; mso-bidi-language: AR-SA">0.5ρCpi(Uref)^2 In my case, I use the same Cp value in two different models (1:1 exposed wall) which means that it might be the Uref  to cause the Pi with huge difference. The problem is that Uref is not known. It has to be calculated from a Met Office value, which is usually obtained at a height of 10 m/s in open flat countryside. To do this the following relation can be used:     Uref=U10K(Zref)^α    The values of K and a depend on the building terrain (they assume that the Met Office site is in flat open country). Thus the wind pressure can be determined by substituting for Uref.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p> <o:p> </o:p> My question is that how ESP-r defines the Z<SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri','sans-serif'; mso-bidi-font-size: 11.0pt; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 新細明體; mso-fareast-theme-font: minor-fareast; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; mso-ansi-language: EN-GB; mso-fareast-language: ZH-TW; mso-bidi-language: AR-SA">ref  in both models (in ground level and 10th level)?  Does the surface pressure due to wind equal to the pressure at boundary node in ESP-r? Also, is there any arbitrary reference pressure (Pref) used in deriving the surface pressure due to wind which means that the wind pressure at nodes might be given by Pi – Pref = 0.5ρ Cpi (Uref)^2   In addition, I wonder whether the wind speed in the result analysis of ESP-r indicates the wind speed at node or the wind speed from climate data.    Finally, I would like to know if ESRU provide any course on airflow network and CFD related issues recently and how much the price would be? I hope to bring over my simulation projects and have further discussion about them. Sorry for having so many questions in one time and thanks for your kind help.     Regards,   Pei-Chun, Liu        </DIV></DIV></DIV> <DIV id=idSignature56178 dir=ltr> <DIV>PhD Student Sustainable Research Building School of the Built Environment University of Nottingham NG7 2RD <DIV></DIV> <DIV>Tel: +44 (0)115 84 67262 Email: laxpcl@nottingham.ac.uk <DIV></DIV></DIV></DIV></DIV> This message has been checked for viruses but the contents of an attachment may still contain software viruses which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation. </BODY> This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation. </HTML>