?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F400%2F&rft.title=The+Dynamics+of+a+Roll+Press+Nip&rft.creator=Fitt%2C+A.D.&rft.creator=Schwendeman%2C+D.&rft.subject=Materials&rft.description=The+problem+presented+concerned+the+dynamics+of+a+roll+press+nip%2C+a+crucial+component+in+a+paper-making+machine.+Modern+commercial+paper-making+machines+are+huge+items+of+equipment.+They+may+be+as+long+as+a+football+field+and+cost+many+millions+of+dollars+each.+Integrity+of+the+process+is+extremely+important%3B+the+paper+in+such+a+machine+travels+so+fast+(up+to+20+km%2Fsec)+that+a+break+is+viewed+as+a+major+calamity+and+may+take+many+man-hours+and+dollars+to+recover+from.+The+size+and+speed+of+the+machines+means+that+it+is+not+easy+to+make+measurements+as+the+paper+passes+through.+The+hostility+of+the+environment+therefore+dictates+that+a+thorough+theoretical+understanding+of+the+important+parts+of+the+process+is+crucial+if+the+processes+involved+are+to+be+optimized.%0D%0A%0D%0AIn+this+study+we+do+not+seek+to+answer+anyone+specific+question%2C+but+rather+wish+to+propose+a+general+framework+for+modeling+the+flow+and+deformation+under+a+roll+press+nip.+Because+of+the+difficulty+of+making+measurements+in+the+nip+region+and+the+need+to+closely+control+the+process%2C+the+distributions+of+pressure%2C+velocity+and+felt+porosity+within+the+nip+have+traditionally+been+subjects+of+great+debate.+%0D%0A%0D%0APrevious+treatments+have+included+lubrication+theory+models+and+%22Bernoulli%22+based+models.+Although+some+progress+may+be+made+using+thin+layer+theory%2C+we+shall+show+the+required+modeling+does+not+take+the+form+of+standard+lubrication+theory.+As+far+as+models+based+on+Bernoulli's+equation+are+concerned%2C+we+simply+note+that+the+discussion+below+shows+that+the+drag+force+exerted+by+the+felt+on+the+liquid+is+a+key+physical+component+of+the+flow+process.+Clearly%2C+a+full+three-phase+flow+treatment+is+required.+In+this+study+we+will+thus+address+the+following+questions%3A%0D%0A%0D%0A(i)+Is+it+possible+to+propose+a+general+theoretical+treatment+of+the+roll+press+nip%3F%0D%0A(ii)+What+determines+the+physics+of+the+water+movement+within+the+paper+and+felt+in+the+roll+press+nip+and+how+is+this+connected+to+the+details+of+the+air+movement+and+the+deformation+of+the+felt%3F%0D%0A(iii)+When+a+general+model+has+been+proposed%2C+is+it+possible+exploit+the+geometry+within+the+nip+to+generate+some+simple+exact+solutions%3F%0D%0A(iv)+What+are+the+key+non-dimensional+parameters+in+the+problem+and+how+large+are+they+likely+to+be+for+realistic+paper-making+machines%3F%0D%0A%0D%0AA+further+matter+of+interest+concerns+the+influence+that+the+size%2C+shape+and+separation+of+the+rollers+have+on+the+whole+process.+We+approach+the+modeling+from+a+rather+general+point+of+view%2C+beginning+by+including+all+effects+that+might+be+important+and+then+making+clearly+defined+assumptions+to+simplify+the+equations.+In+this+way+it+is+possible+to+make+changes+to+the+model+if+circumstances+change.&rft.date=1999&rft.type=Study+Group+Report&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F400%2F1%2FThe-dynamics-of-a-roll-press-nip.pdf&rft.identifier=++Fitt%2C+A.D.+and+Schwendeman%2C+D.++(1999)+The+Dynamics+of+a+Roll+Press+Nip.++%5BStudy+Group+Report%5D+++++