dr_mat 0 Posted December 19, 2006 Ah, ok, the Cambridge one. Don't know much about cambs general SC resource, but the astrophysics dept have a big Altix... Cost per MHz isn't what's most interesting, btw, it's $ per GFLOP that's most interesting, and then it gets a lot closer than you'd think. And then there's the application itself... There's always going to be a premium for doing NUMA in hardware, that's inevitable, but it depends on the application workload. So-called "embarrassingly parallel" applications (e.g. ray tracing) scale up regardless of the interconnect used - and PC clusters are GREAT for this stuff. But apps that do a LOT of inter-process communication hit a scaling brick wall unless your interconnect is phenomenally quick .. I've seen cases where an app running on pc clusters on 512 cores runs SLOWER than running it on 64 cores. Of course in those cases we sell 'em an Altix and it runs many many times quicker. :) Quote Share this post Link to post Share on other sites
Crispy 0 Posted December 19, 2006 Just to stir it up a bit - surely by decreasing lift, there is a subsequent increase in downforce? :wink: Or is that just poor terminology.... Not "poor terminology", just "utter ****". ;) ehh...it's actually more or less right!... lift coefficient = negative downforce coefficient. Car produces lift (neg df) at speed. The spolier is designed to "spoil" or reduce the lift coeff, therefore decreasing the negative downforce (lift) produced! It's the same term...just the opposite sense!....so saying the spolier increases downforce isn't actually "wrong" Ha. utter.... Ta Quote Share this post Link to post Share on other sites
corozin 0 Posted December 19, 2006 Are there enough anoraks available in the UK for all the pedants on this thread ?? :) Quote Share this post Link to post Share on other sites
Andy665 0 Posted December 19, 2006 Very few road cars on sale actually generate downforce and recent years have seen a move to minimising lift taking place on cleaning up the airflow under the car, in some cases helping to achieve zero lift or a tiny amount of downforce. Something which hasn't been mentioned in terms of aerodynamic qualities of vehicles is the far more relevant CDa, the frontal area of any given vehicle has as much if not more to do with overall aerodynamic efficiency. Sorry to be an anorak but the Calibra had a CD of 0.26 but only for the 2.0 8V steel wheeled version, the wider tyres and alloy wheels of the 16V increased the CD to 0.28. Quote Share this post Link to post Share on other sites
Yandards 0 Posted December 19, 2006 Quality thread this! (Plenty of anoraks John!) CDa is a type of zero lift drag, basically it is form drag - the shape of an object the creates drag. Surface friction drag is also a type of zero lift drag (get those clay bars out!) and so is interference drag - where to airflows meet up again, i.e. the air at the back of the car coming from underneath and over the top. It is a shame you can not model the underside of the C accurately as I feel that the shape of the rear bumper really does some nasty things to airflow at speed. Quote Share this post Link to post Share on other sites
dr_mat 0 Posted December 19, 2006 It is a shame you can not model the underside of the C accurately as I feel that the shape of the rear bumper really does some nasty things to airflow at speed. Interesting you mention this, but remember the previous mondeo shape? I seemed to see hundreds of those with split rear bumpers flapping around at one side on the motorways. It looked very much like the bumper was acting as a bit of a parachute.. Quote Share this post Link to post Share on other sites
Yandards 0 Posted December 19, 2006 It is a shame you can not model the underside of the C accurately as I feel that the shape of the rear bumper really does some nasty things to airflow at speed. Interesting you mention this, but remember the previous mondeo shape? I seemed to see hundreds of those with split rear bumpers flapping around at one side on the motorways. It looked very much like the bumper was acting as a bit of a parachute.. Yes I do, still see some around suffering from the same problem. The Cs rear bumper is a lot stiffer than the mundano item though but I would still expect some flex at speed. Most of the underside of the C is not the best when you think about it. I suppose the front splitter helps to a degree but from the back of the floor pan back it is not an ideal shape to ensure smooth airflow, especially the scoop shape of the rear bumper. I suppose you could always fit rear bumper vents :pukeright: I still think the Corrado has excellent aerodynamics though, if you think about the amount of wind buffet you get on motorways when it is windy there is very little when compared to other cars - especially the modern trend for designing high boxes on wheels. Quote Share this post Link to post Share on other sites
dr_mat 0 Posted December 19, 2006 Most of the underside of the C is not the best when you think about it... I still think the Corrado has excellent aerodynamics though, if you think about the amount of wind buffet you get on motorways when it is windy there is very little when compared to other cars - especially the modern trend for designing high boxes on wheels. Most modern cars have a load of plastic panelling underneath to try and smooth the air flow. The C was "old skool".. i.e. "cheap and nasty". I think the C's stability in cross winds is more about it weighing a stack load more than anything else it's age, and it being a bit squat compared to the cornflake boxes people buy now.. :) It's general aerodynamics are very much an afterthought (the spoiler for example)! Quote Share this post Link to post Share on other sites
corozin 0 Posted December 19, 2006 Very few road cars on sale actually generate downforce and recent years have seen a move to minimising lift taking place on cleaning up the airflow under the car, in some cases helping to achieve zero lift or a tiny amount of downforce. My car generates loads of downforce, but only when I'm sitting it it :D Quote Share this post Link to post Share on other sites
Yandards 0 Posted December 19, 2006 Very few road cars on sale actually generate downforce and recent years have seen a move to minimising lift taking place on cleaning up the airflow under the car, in some cases helping to achieve zero lift or a tiny amount of downforce. My car generates loads of downforce, but only when I'm sitting it it :D PMSL Quote Share this post Link to post Share on other sites
davidwort 0 Posted December 20, 2006 Most modern cars have a load of plastic panelling underneath to try and smooth the air flow. The C was "old skool".. i.e. "cheap and nasty". ... It's general aerodynamics are very much an afterthought (the spoiler for example)! they didn't do too badly, as the mk5 golf has the same drag coeff. Quote Share this post Link to post Share on other sites
dr_mat 0 Posted December 21, 2006 The mk5 golf is about a foot and a half taller (not to mention wider and lower), and frontal surface area is a huge part of the drag calculations, so actually that doesn't paint such a rosy picture of the Corrado's aerodynamics at all! Quote Share this post Link to post Share on other sites
Yandards 0 Posted December 21, 2006 The mk5 golf is about a foot and a half taller (not to mention wider and lower), and frontal surface area is a huge part of the drag calculations, so actually that doesn't paint such a rosy picture of the Corrado's aerodynamics at all! True but would you want a mk5 instead? :wink: The other thing is we are talking about a design that was being crash tested over 20 years ago, computer modelling for anything at all on the car was pretty much out of the question. Quote Share this post Link to post Share on other sites
Henny 0 Posted December 21, 2006 Oh, and just to point a little thing out about the Calibra, it was only the base model 16V version that had a really low drag co-efficient rating... they had to put a spoiler on the bigger engined/Turbo versions which made the rating a LOT closer to that of the Corrado... ;) Wonder why they had to put a spoiler on the back?!? ;) :lol: Quote Share this post Link to post Share on other sites
dr_mat 0 Posted December 21, 2006 Ahem, Henny, someone already mentioned that .. ;) Quote Share this post Link to post Share on other sites
Henny 0 Posted December 21, 2006 rats.... the joys of not having internet access at home and shed loads of work to do means that I don't always get chance to read every post anymore... :( Quote Share this post Link to post Share on other sites
dr_mat 0 Posted December 21, 2006 I'm just wondering how many more VWs you can buy and put (nearly) the same wheels on! Quote Share this post Link to post Share on other sites
