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Ian A. Frigaard Professor, Applied Mathematics & Mechanical Engineering Research Overview

My research interests are in non-Newtonian fluid mechanics and understanding industrial processes that exploit the non-Newtonian properties of fluids. In particular I am interested in the mechanics of visco-plastic (yield stress) fluids. Many of the industrial research projects come from the petroleum industry. Methodologically, my group conducts research that combines mathematical, experimental and computational approaches. Many of the results of our research are described the publications of my group and our research collaborators. Research is carried out in the complex fluids lab at UBC, in a strongly interdisciplinary environment. Areas of interest have included the following (many of which overlap with one another): Oilfield cementing fluid mechanics: primary cementing and plug cementing Bubbles and particles in yield stress fluids Hydrodynamic instabilities in visco-plastic fluids Displacement flows, dispersion and mixing with generalised Newtonian fluids Mathematical Modelling of Industrial Processes Visco-plastic lubrication flows Restarting waxy crude oil pipelines I am always interested to hear of new applications for yield stress fluids, whether of industrial, biological, geophysical or other origin. Applied industrial problems that are not suitable for academic research may be dealt with via consultancy.

Oilfield cementing fluid mechanics: Go to top Research sponsors: - Schlumberger - NSERC - BC Oil & Gas Commission	This has been a major activity area for my group over the past many years. ü In primary cementing we have extensively studied laminar displacement flows in annuli, looking at the effects of standoff (eccentricity), inclination, casing movement flow rate and fluid rheology on the ability to remove drilling mud and steadily displace annular sections. ü We have a lab-scale annulus suitable for experimental displacements flows, inclinable to any angle. We run experiments using clear lab fluids (typically weighted Carbopol, xanthan or glycerin solutions) with dimensionally similar rheological properties to wellbore fluids. ü We have looked closely at displacement flows in simplified sections of the annulus (plane channels), to study the formation of residual mud layers (i.e. micro-annulus). ü We have looked at the possibility of using chemically reactive spacer systems to improve displacement efficiency through the instigation of local instability and mixing ü In plug cementing, we have studied the stability of plugs that are set off-bottom addressing the question of what physical properties are needed in order for viscous pills and cement slurries to remain stationary after placement with a less dense fluid beneath. ü In near horizontal wells we have estimated the distance that a plug may slump and have performed similar estimates for horizontal annuli. ü In pumping down the casing we have an ongoing study to establish whether two given fluids displace effectively or destabilise and mix. We have developed estimates for the speed of the displacement front and the displacement efficiency, in various situations. ü We have studied pipe flows where a fluid with large yield stress is displaced by a much less viscous Newtonian fluid, e.g. water though gelled drilling mud.
	Relevant work: S.M. Taghavi, I.A. Frigaard, “Estimation of mixing volumes in buoyant miscible displacement flows along near-horizontal pipes.” Can. J. Chem. Eng., accepted for publication, to appear 2012.
	M. Moyers-Gonzalez, K. Alba, S.M. Taghavi, I.A. Frigaard, “Fluid-fluid displacement flows in pipes: development of a semi-analytical closure for stratified interfaces.” J. non-Newt. Fluid Mech., accepted for publication, to appear 2012.
	S.M. Taghavi, K. Alba, I.A. Frigaard, “Buoyant miscible displacement flows at moderate viscosity ratios and low Atwood numbers in near-horizontal ducts.” Chem. Eng. Sci., 69(1), pp. 404-418, (2012).
	S.M. Taghavi, K. Alba, T. Seon, K. Wielage-Burchard, D.M. Martinez, I.A. Frigaard, “Miscible displacement flows in near-horizontal ducts at low Atwood number.” J. Fluid Mech., doi:10.1017/jfm.2012.26, (2012).
	S.M. Taghavi, K. Alba, M. Moyers-Gonzalez, I.A. Frigaard, “Incomplete fluid–fluid displacement of yield stress fluids in near-horizontal pipes: Experiments and theory.” J. non-Newt. Fluid Mech., 167–168, pp. 59-74, (2012).
	S.M. Taghavi, T. Seon, D.M. Martinez, K. Wielage-Burchard and I.A. Frigaard, “Stationary residual layers in buoyant Newtonian displacement flows.” Phys. Fluid., 23, 044105 (2011).
	T. Burghelea and I.A. Frigaard, “Unstable parallel flows triggered by a fast chemical reaction.” J. non-Newt. Fluid Mech., 166, (9-10), pp. 500-514 (2011)
	K. Wielage-Burchard and I.A. Frigaard, “Static wall layers in plane channel displacement flows.” J. non-Newt. Fluid Mech., 166 (5-6), pp. 245-261 (2011).
	S.M. Taghavi, T. Seon, D.M. Martinez and I.A. Frigaard, “Influence of an imposed flow on the stability of a gravity current in a near horizontal duct.” Phys. Fluid., 22, 031702, (2010).
	S. Malekmohammadi, M.F. Naccache, I.A. Frigaard and D.M. Martinez, “Buoyancy driven slump flows of non-Newtonian fluids in pipes.” J. of Petr. Sci. Engng., 72(3-4), PP. 236-243, (2010).
	M. Carrasco-Teja and I.A. Frigaard, “Non-Newtonian fluid displacements in horizontal narrow eccentric annuli: Effects of motion of the inner cylinder.” J. Fluid Mech., 653, pp. 137-173 (2010).
	S. Malekmohammadi, M. Carrasco-Teja, S. Storey, I.A. Frigaard and D.M. Martinez, “An experimental study of displacement flow phenomena in narrow vertical eccentric annuli.” J. Fluid Mech., 649, pp. 371-398 (2010).
	I.A. Frigaard & G.A. Ngwa, “Slumping flows in annuli: design of chemical packers & cementing of subsurface pipes.” Invited paper, Trans. Por. Media, doi:10.1007/s11242-009-9467-1, (2009).
	S.M. Taghavi, T. Seon, D.M. Martinez and I.A. Frigaard, “Buoyancy-dominated displacement flows in near-horizontal channels: the viscous limit.” J. Fluid Mech., 639, pp. 1-35, (2009).
	M. Moyers-Gonzalez and I.A. Frigaard, “Kinematic instabilities in two-layer eccentric annular flows, part 2: shear thinning and yield stress effects, J. of Engng. Math., 65(1), pp. 25-52, (2009)
	M. Carrasco-Teja and I.A. Frigaard, “Displacement flows in horizontal, narrow, eccentric annuli with a moving inner cylinder.” Phys. Fluids, 21 073102 (2009).
	M. Carrasco-Teja, I. Frigaard, B. Seymour and S. Storey, “Visco-plastic fluid displacements in horizontal narrow eccentric annuli” J. Fluid Mech. 605, pp. 293-327 (2008).
	M. Moyers-Gonzalez and I.A. Frigaard, “Kinematic instabilities in two-layer eccentric annular flows, part 1: Newtonian fluids”, J. of Engng. Math., 62(2), pp. 103-131, (2008).
	T. Burghelea, K. Wielage-Burchard, I. Frigaard, D.M. Martinez and J, Feng. “A novel low inertia shear flow instability triggered by a chemical reaction” Phys. Fluids, 19, 083102 (2007).
	M.A. Moyers-Gonzalez, I.A. Frigaard, O. Scherzer & T.-P. Tsai, “Transient effects in oilfield cementing flows, part 1: qualitative behaviour”, Euro. Jnl. Appl. Math. 18, pp. 477-512, (2007)
	S. Pelipenko and I.A.Frigaard, “Two-dimensional computational simulation of eccentric annular cementing displacements.” IMA Journal of Applied Mathematics, 69: pp. 557-583, (2004).
	S. Pelipenko and I.A.Frigaard, “Visco-plastic fluid displacements in near-vertical eccentric annuli: lubrication modelling.” J. Fluid Mech., 520, pp.343-377, (2004).
	I.A. Frigaard and G. Ngwa, “Upper bounds on the slump length in plug cementing of near-horizontal wells” J. of Non-Newtonian Fluid Mech., 117(2-3), pp. 147-162, (2004).
	S. Pelipenko and I.A.Frigaard, “On steady state displacements in primary cementing of an oil well.” J. of Engng. Math., 48(1), pp. 1-26, (2004).
	S. Bittleston, J. Ferguson & I.A. Frigaard, “Mud removal and cement placement in primary cementing of an oil well.” Invited paper, J. Engineering Mathematics, 43, pp. 229-253 (2002).
	I.A. Frigaard, M. Allouche & C. Gabard, “Setting rheological targets for chemical solutions in mud removal & cement slurry design.” Journal of Petroleum Technology, 53(8), pp. 65-66 (2001).
	I.A. Frigaard, O. Scherzer & G. Sona, “Uniqueness & non-uniqueness in the steady displacement of two visco-plastic fluids.” ZAMM, 81(2), pp. 99-118, (2001).
	M. Allouche, I.A. Frigaard & G. Sona, “Static wall layers in the displacement of two visco-plastic fluids in a plane slot.”, J. Fluid Mech. 424, pp. 243-277, (2000).
	I.A. Frigaard & O. Scherzer, “The effects of yield stress variation on uniaxial exchange flows of two Bingham fluids in a cylindrical duct.” SIAM J. Appl. Math., 60(6), pp. 1950-1976, (2000).
	H. Fenie & I.A. Frigaard, “Transient fluid motions in a simplified model for oilfield plug cementing.” Mathematical and Computer Modelling, 30(7-8), pp. 71-91, (1999).
	I.A. Frigaard & J.P. Crawshaw, “Preventing buoyancy driven flows of two Bingham fluids in a closed pipe: fluid rheology design for oilfield plug.” J. Engng. Math., 36(4), pp. 327-348, (1999).
	I.A. Frigaard & O. Scherzer, “Uniaxial flows of two Bingham fluids in a cylindrical duct.” IMA J. Appl. Math., 61, pp. 237-266, (1998).
	I.A. Frigaard, “Stratified exchange flows of two Bingham fluids in an inclined slot.” J. Non-Newtonian Fluid Mech., 78, pp. 61-87, (1998).
	S.M. Taghavi, K. Alba, I. Frigaard “Weakly-inertial Buoyant Displacement Flows In Near-horizontal Channels”, in proc. 23rd Canadian Congress of Applied Mechanics, 2011, Vancouver.
	K. Alba, S.M. Taghavi, S. Gharib, T. Seon, M. Martinez and I. Frigaard “Displacement flow of shear thinning fluids in tube: The effect of density and viscosity ratio”, paper number IMECE2010-37939, American Society of mechanical Engineers International Congress and Exposition, held in Vancouver, November 12-18, 2010.
	K. Alba, S.M. Taghavi, S. Gharib, T. Seon, M. Martinez and I. Frigaard “Miscible two-fluid displacement flows in a near-horizontal pipe”, proceedings Canadian Society for Mechanical Engineering, Forum, Victoria, June 7 – 9, 2010.
	M. Carrasco-Teja, I.A. Frigaard & B. Seymour, “Cementing Horizontal Wells: Complete Zonal Isolation Without Casing Rotation” Society of Petroleum Engineers paper: SPE 114955, (2008).
	D.J. Guillot, J. Desroches and I. Frigaard, “Are preflushes really contributing to mud displacement during primary cementing?” Society of Petroleum Engineers paper: SPE/IADC 105903, (2007).
	S. Pelipenko and I.A.Frigaard, “Effective and Ineffective Strategies for Mud Removal and Cement Slurry Design.” Society of Petroleum Engineers paper number: SPE 80999, (2003).
	I.A. Frigaard, M. Allouche & C. Gabard, “Incomplete Displacement of Viscoplastic Fluids in Slots and Pipes-Implications for Zonal Isolation.” Society of Petroleum Engineers paper number: SPE 64998, February (2001).
	S.W. Fosso, M. Tina, I.A. Frigaard & J.P. Crawshaw, “Viscous-pill Design Methodology leads to Increased Cement Plugs Success Rates: Application and Case Studies from Southern Algeria.” Society of Petroleum Engineers paper number: SPE 62752, September 2000.
	J.P. Crawshaw & I.A. Frigaard, “Cement Plugs; Stability and Failure by a Buoyancy-driven Mechanism.” Society of Petroleum Engineers paper number: SPE 56959, (1999).

Bubbles and particles in yield stress fluids: Go to top Research sponsors: - NSERC - Schlumberger	There are different facets to this research ü We have carried out sedimentation experiments for particles and bubble rise experiments. ü We have made variational estimates of the critical yield stresses necessary to prevent bubbles from rising ü We have made analytical estimates and computations for the critical yield stresses required to prevent particles from sedimenting. ü We have produced analytical results relating to existence, uniqueness, symmetry of solutions, etc.. ü I have ideas I’d like to exploit further on computing suspension flows in yield stress fluids. ü The static stability computations lead to novel methods for fractionation of particles, applied to the pulp and paper industry ü We are studying the deposition of thick mined tailings in laminar flows ü We are studying dispersion of proppant along pipe and channel geometries
	Relevant work: A. Madani, S. Storey, J.A. Olson, I.A. Frigaard, J. Salmela and D.M. Martinez, “Fractionation of rod-like particle suspensions in a viscoplastic fluid.” Chem. Eng. Sci. 65(5), pp. 1762-1772 (2010).
	A. Putz and I.A. Frigaard, “Creeping flow around particles in a Bingham fluid” J. non-Newt. Fluid Mech., 165(5-6), pp. 263-280 (2009).
	A. Putz, T. Burghelea, D.M. Martinez and I.A. Frigaard, “Settling of an isolated spherical particle in a yield stress shear thinning fluid”, Physics of Fluids, 20, 033102 (2008)
	N. Dubash and I. Frigaard, “Propagation and stopping of air bubbles in Carbopol”, J. Non-Newtonian Fluid Mech., 142, pp. 123–134, (2007)
	N. Dubash, and I.A. Frigaard, “Conditions for static bubbles in visco-plastic fluids.” Physics of Fluids, 16(12), pp. 4319-4330, (2004).

Hydrodynamic instabilities in visco-plastic fluids: Go to top Research sponsors: - NSERC - Schlumberger	This has been an area of interest for more than 20 years. It all started with my masters thesis: a long time ago, in a galaxy far, far away…. ü Methodology for linear stability in yield stress fluids, treating the yield surface perturbation correctly. ü Energy stability methods for nonlinear stability ü Various approximation method to derive bounds for stability ü Plane Poiseuille flow, Hagen-Poiseuille flow ü Taylor-Couette flow ü Rayleigh-Bénard flow ü Experimental studies of Hagen-Poiseuille flow and empirical rules for transition ü Numerous studies of multi-layer flow stability.
	Relevant work: S. Hormozi and I.A. Frigaard, “Nonlinear stability of a visco-plastically lubricated viscoelastic fluid flow.” J. non-Newt. Fluid Mech., 169–170, pp. 61-73, (2012).
	A. Madani, D.M. Martinez, J.A. Olson, I.A. Frigaard, “The stability of spiral Poiseuille flows of Newtonian and Bingham fluids in an annular gap.” J. non-Newt. Fluid Mech., doi.org/10.1016/j.jnnfm.2012.02.007, (2012).
	M. Moyers-Gonzalez, I.A. Frigaard and C. Nouar, “Stable two-layer flows at all Re; visco-plastic lubrication of shear-thinning and viscoelastic fluids.” J. non-Newt. Fluid Mech., 165, (23-24), pp. 1578-1587, (2010).
	M. Moyers-Gonzalez and I.A. Frigaard, “Kinematic instabilities in two-layer eccentric annular flows, part 2: shear thinning and yield stress effects, J. of Engng. Math., 65(1), pp. 25-52, (2009)
	B. Güzel, I. Frigaard, D.M. Martinez “Predicting laminar–turbulent transition in Poiseuille pipe flow for non-Newtonian fluids”, Chem. Eng. Sci. 64(2), pp. 254-264, (2009).
	C. Metivier, I.A. Frigaard and C. Nouar, “Non-linear stability of the Bingham Rayleigh-Benard flow”, J. non-Newtonian Fluid Mech., 158(1-3), pp. 127-131, (2009).
	B. Guzel, T. Burghelea, I. A. Frigaard and D. M. Martinez, “Observation of laminar-turbulent transition of yield stress fluid in Hagen-Poiseuille flow”, J. Fluid Mech., 627, pp. 97- 128 (2009).
	M. Moyers-Gonzalez and I.A. Frigaard, “Kinematic instabilities in two-layer eccentric annular flows, part 1: Newtonian fluids”, J. of Engng. Math., 62(2), pp. 103-131, (2008).
	T. Burghelea, K. Wielage-Burchard, I. Frigaard, D.M. Martinez and J, Feng. “A novel low inertia shear flow instability triggered by a chemical reaction” Phys. Fluids, 19, 083102 (2007).
	J.Y. Zhang, I. Frigaard and D. Vola, “ Yield stress effects on Rayleigh-Benard convection” J. Fluid Mech. 566, pp. 389-419, (2006).
	M.P. Landry, I.A. Frigaard & D.M. Martinez, “Stability and instability of Taylor-Couette flows of a Bingham fluid” J. Fluid Mechanics, 560, pp. 321-353, (2006).
	I.A. Frigaard and C. Nouar, “On the usage of viscosity regularisation methods for visco-plastic fluid flow computation” J. Non-Newtonian Fluid Mech., 127(1), pp. 1-26, (2005).
	M. Moyers-Gonzalez, I.A. Frigaard and C. Nouar, “Nonlinear stability of a visco-plastically lubricated shear flow.” Journal of Fluid Mechanics, 506, pp.117-146, (2004).
	I.A. Frigaard and C. Nouar, “On three-dimensional linear stability of Poiseuille flow of Bingham fluids.” Physics of Fluids, 15(10), pp. 2843-2851, (2003).
	C. Nouar & I.A. Frigaard, “Nonlinear stability of Poiseuille flow of a Bingham fluid.” J. Non-Newtonian Fluid Mech., 100, pp. 127-149, (2001).
	I.A. Frigaard, “Super-stable parallel flows of multiple visco-plastic fluids.” J. Non-Newtonian Fluid Mech., 100, pp. 49-76, (2001).
	I.A. Frigaard, S.D. Howison & I.J. Sobey, “On the stability of Poiseuille flow of a Bingham fluid.” J. Fluid Mech., 263, pp. 133-150, (1994).
	I.A. Frigaard and C. Nouar, “Predicting Transition to Turbulence in Well Construction Flows.” Society of Petroleum Engineers paper number: SPE 81150, (2003).

Displacement flows, dispersion and mixing with generalised Newtonian fluids: Go to top Research sponsors: - Schlumberger - NSERC

The majority of this work has been in conjunction with the study of oilfield cementing displacements and waxy crude oil restarts. See also: J.Y. Zhang and I.A. Frigaard, “Dispersion effects in the miscible displacement of two fluids in a duct of large aspect ratio”, Journal of Fluid Mechanics, 549, pp. 225–251, (2006)

Mathematical Modelling of Industrial Processes: Go to top Research sponsors: - NSERC - Firebird - Schlumberger MITACS	Various processes have attracted my attention over the years. Some of this work is undertaken as consulting. ü Spray-forming of Aluminium billets ü Well control ü Czrochalski crystal growth ü Image processing using nonlinear diffusion filters ü Injection molding ü Oilfield cementing ü Waxy crude oil pipelining ü Pile grouting ü Sand control/gravel packing ü Fracturing flows ü Fouling ü Solidification of alloys ü Fiber flows in pulp and paper processing ü Different process-related hydrodynamic stabilities
	Relevant work: K. Pougatch and I.A. Frigaard, “Thin film flow on the inside surface of a horizontally rotating cylinder: steady state solutions and their stability.” Phys. Fluids., 23, 022102 (2011)
	N. Dubash, I.A. Frigaard and B. Stoeber, “An oscillatory flow phenomenon in microtube flows of thermally responsive fluids”, J. Engng. Math., DOI: 10.1007/s10665-010-9404-x
	A. Guha and I.A. Frigaard, “On the stability of plane Couette-Poiseuille flow with uniform crossflow.” J. Fluid Mech., 656, pp. 417-447 (2010).
	A. Wachs, G. Vinay & I. Frigaard, “1.5D model for start up of weakly compressible viscoplastic and thixotropic fluid in pipelines”, J. non-Newt. Fluid Mech., 159(1-3), pp. 81-94, (2009).
	C.S. Bohun, I. Frigaard, H. Huang & S. Liang, “A Semi-Analytical Model for InSb Crystal Growth.” SIAM J. Appl. Math., SIAM J. Appl. Math. 66(5), pp. 1533-1562, (2006).
	I.A.Frigaard & O. Scherzer, “Herschel-Bulkley diffusion filtering: non-Newtonian fluid mechanics in image processing” ZAMM, 86(6), pp. 474-494, (2006).
	G. Lewis, I. Frigaard, H. Huang, T. Myers, R. Westbrook & M. Carrasco-Teja, “Simple models for an injection molding system”, Can. Appl. Math. Quart., 12(4), pp. 491, (2004).
	J. Olson, I.A. Frigaard, C. Chan and J.P. Hämäläinen, “Modelling a turbulent fibre suspension flowing in a planar contraction: the 1D” Int. J. Multi-phase Flows, 30(1), pp. 51-66, (2004).
	I.A.Frigaard, G. Ngwa and O. Scherzer, “On effective stopping time selection for visco-plastic nonlinear BV diffusion filters.” SIAM J. Appl. Math., 63(6), pp. 1911-1934, (2003).
	I.A. Frigaard & O. Scherzer, “Spraying the perfect billet.” SIAM J. Appl. Math., 57(3), pp. 649-682, (1997).
	I.A. Frigaard, “Solidification of Spray-formed Aluminium billets; heat flow in the bulk deposit.” J. Engng. Math. 31, pp. 411-437, (1997).
	I.A. Frigaard, “Solidification of spray-formed Aluminium Billets; an Analysis of Thin layering Effects.” J. Engng. Math. 30, pp. 417-443, (1996).
	I.A. Frigaard, “Growth dynamics of spray-formed Aluminium billets, part 2; transient billet growth.” J. Materials Processing and Manufacturing Science, 3(3), pp. 257-275, (1995).
	I.A. Frigaard, “The dynamics of spray-formed billets.” SIAM J. Appl. Math., 55(5), pp. 1161-1203, (1995).
	I.A. Frigaard, “Growth dynamics of spray-formed Aluminium billets, part 1; steady state crown shapes.” J. Materials Processing and Manufacturing Science, 3(2), pp. 173-192, (1994).
	A.C Fowler, I.A. Frigaard & S.D. Howison, “Temperature Surges in Current-limiting Circuit Devices.” SIAM J. Appl. Math., 52(4), pp. 998-1011, (1992).
	A. Guha and I.A. Frigaard, “Stability analysis of plane Couette-Poiseuille flow in presence of cross-flow”, proceedings of the Canadian Society for Mechanical Engineering, Forum, held in Victoria, June 7 – 9, 2010.
	G. Vinay, A. Wachs and I. Frigaard, “Start-up of gelled waxy crude oil pipelines: a new analytical relation to predict the restart pressure.” Soc. Petrol. Eng. paper number: SPE 122443, (2009).
	C.S. Bohun, I.A. Frigaard, H.X. Huang “A perturbation model for the growth of type III-V compound crystals” proceedings of Conference on Differential Equations and Asymptotic Theory in Mathematical Physics, OCT 20-29, 2003 Wuhan Univ, Wuhan, Peoples Republic China. Appeared in Differential Equations & Asymptotic Theory Mathematical Physics Book Series: Series In Analysis, Vol. 2  Pages: 263-279   Published: 2004
	I.A. Frigaard, N.L. Humphries, I.M. Rezmer-Cooper and J.P. James, “High Penetration Rates: Hazards and Well Control.” Society of Petroleum Engineers paper number: SPE 37593, (1997).
	I.A. Frigaard, “Controlling the Growth of Aluminium Spray-formed Billets.” in Sprayforming, eds. K. Bauckhage and V. Uhlenwinkel, Universität Bremen, ISBN 3-88722-388-8, pp. 29-43, (1997).
	I.M. Rezmer-Cooper, J. James, P. Fitzgerald, A.B. Johnson, D.H. Davies, I.A. Frigaard, S. Cooper, Y. Luo and P. Bern, “Complex Well Control Events Accurately Represented by an Advanced Kick Simulator.” Society of Petroleum Engineers paper number: SPE 36829, (1996).
	I.A. Frigaard, “Growing Spray-formed Aluminium Billets.” Proceedings, ECMI94 conference, ed. H. Neunzert, Wiley/Teubner, pp. 389-396, (1996).

Visco-plastic lubrication flows: Go to top Research sponsors: - NSERC	This has been a major activity area for my group over the past many years. ü With inelastic fluids we can achieve stable multi-layer shear flows at high Re by placing an unyielded layer at the interface ü We have a lab-scale multi-layer flow loop dedicated to this research. We run experiments using clear lab fluids (typically weighted Carbopol, xanthan or glycerin solutions) with dimensionally similar rheological properties to industrial fluids. ü For core-annular flows we have a wide range of experimental flows showing this stability, including visco-elastic core fluids ü We have proven linear and nonlinear stability ü We have studied start-up and development lengths ü With special configurations we can achieve linearly stable flows at infinite Re! ü We have ideas for how to engineer hydrodynamically stable core-annular oil-water flows ü We have preliminary work on controlling shape of core fluids, stably frozen in after controlled oscillation. ü The same methodology leads to droplet encapsulation, but with the novelty of no capillary length-scale! ü We are looking at applications in food industry, polymer processing, paper coating, oil and gas.
	Relevant work: S. Hormozi and I.A. Frigaard, “Nonlinear stability of a visco-plastically lubricated viscoelastic fluid flow.” J. non-Newt. Fluid Mech., 169–170, pp. 61-73, (2012).
	S. Hormozi, D.M. Martinez, I.A. Frigaard, “Stable core-annular flows of viscoelastic fluids using the visco-plastic lubrication technique.” J. non-Newt. Fluid Mech., 166 (23–24), pp. 1356-1368 (2011).
	S. Hormozi, K. Wielage-Burchard and I.A. Frigaard, “Entry, start up and stability effects in visco-plastically lubricated pipe flows.” J. Fluid Mech., 166 (5-6), pp. 262-278 (2011).
	S. Hormozi, K. Wielage-Burchard and I.A. Frigaard, “Multi-layer channel flows with yield stress fluids.” J. non-Newt. Fluid Mech. 166, (5-6), pp. 262-278 (2011)
	M. Moyers-Gonzalez, I.A. Frigaard and C. Nouar, “Stable two-layer flows at all Re; visco-plastic lubrication of shear-thinning and viscoelastic fluids.” J. non-Newt. Fluid Mech., 165, (23-24), pp. 1578-1587, (2010).
	C.K. Huen, I.A. Frigaard and D.M. Martinez, “Experimental studies of multi-layer flows using a visco-plastic lubricant”, J. Non-Newtonian Fluid Mech., 142, pp. 150–161, (2007)
	M. Moyers-Gonzalez, I.A. Frigaard and C. Nouar, “Nonlinear stability of a visco-plastically lubricated shear flow.” Journal of Fluid Mechanics, 506, pp.117-146, (2004).
	M. Moyers-Gonzalez and I.A. Frigaard, “Numerical solution of duct flows of multiple visco-plastic fluids” J. Non-Newtonian Fluid Mech., 127, pp. 227-241, (2004).
	I.A. Frigaard, “Super-stable parallel flows of multiple visco-plastic fluids.” J. Non-Newtonian Fluid Mech., 100, pp. 49-76, (2001).

Restarting waxy crude oil pipelines: Go to top Research sponsors: - NSERC	This has been an active collaboration with colleagues from IFP, started during sabbatical leave. ü We have identified 3 regimes for start-up, dominated by friction, compressibility and/or acoustic propagation. Most of these timescales for start-up are anyway fast compared with the actual displacement times ü We have also computed compressible displacement flows, using axisymmetric (2D) and reduced models. ü The effects of thixotropy have been explored ü Sometimes it is possible to restart pipelines below the incompressible pressure limit, combining thixotropic and compressible effects ü We are studying this in a reduced model, to try to derive semi-analytical predictions of start-up ü We are investigating different models for compressibility, due to different bubble distributions in the oil phase, and seeing how this affects the yield stress
	Relevant work:
	A. Wachs, G. Vinay & I. Frigaard, “1.5D model for start up of weakly compressible viscoplastic and thixotropic fluid in pipelines”, J. non-Newt. Fluid Mech., 159(1-3), pp. 81-94, (2009).
	I. Frigaard, G. Vinay and A. Wachs “Compressible displacements flows of waxy crude oils in long pipeline startup flows”, J. non-Newtonian Fluid Mech., 147, (1-2), pp. 45-64 (2007).
	G. Vinay, A. Wachs and I. Frigaard, “Start-up transients and efficient computation of isothermal waxy crude oil flows” J. non-Newtonian Fluid Mech., 143, pp. 141-156, (2007)
	G. Vinay, A. Wachs and I. Frigaard, “Start-up of gelled waxy crude oil pipelines: a new analytical relation to predict the restart pressure.” Soc. Petrol. Eng. paper number: SPE 122443, (2009).