Across-wind aerodynamic parameters of tall chimneys with circular cross section - a new empirical model

The prediction of across-wind response of circular cylinders remains a chal lenging task, despite extensive research efforts. An attempt has been made to correlate the rms lift coefficient due only to vortex shedding, C'(L,VS) both in wind tunnel and full-scale conditions by separating the local rms lift coefficient, C'(L), into two components, one due to the lateral turbul ence and the other due to the vortex shedding. Based on the literature, and also using test results measured by the authors, it is found that the fina l value of C'(L,V), as discussed in the paper, show a mean value of 0.089 w ith a coefficient of variation of 18%, independent of Reynolds number regim e. The above value plus 1.66 times the standard deviation gives a value of 0.115 which is in excellent agreement with the value of C'(L,VS)=0.12 recom mended for design of chimneys under open terrain conditions, as per the Ind ian Standard Code of Practice: IS: 4998 Part-2, 1992. Further it is shown t hat the Griffin universal Strouhal number, G attains a mean value of 0.065 with a coefficient of variation (cov) of 8%, independent of sub-critical an d trans-critical Reynolds number regime. (C) 2001 Elsevier Science Ltd. All rights reserved.