Flow Hysteresis Research Articles

Oscillation and hysteresis characteristics of high-speed duct during TBCC inlet mode transition under mildly throttled condition

This study aims to investigate the intricate dynamic characteristics of the high-speed duct during the over-under Turbine-Based Combined Cycle TBCC inlet mode transition process while operating in an off-design state under throttled conditions. A typical over-under TBCC inlet, designed for a working Mach number range of 0–6 with a transition Mach number of 3.5, is examined through experimental studies in a supersonic wind tunnel with a freestream Mach number of 2.9. The investigation focuses on the complex oscillatory flow and unique hysteresis observed in the mode transition process of the high-speed duct under the mildly throttled condition, utilizing high-speed Schlieren and dynamic pressure acquisition system. The findings reveal that the high-speed duct undergoes four distinct oscillation stages akin to those in a higher throttled state during the mode transition, albeit with smaller dominant frequency and energy. Moreover, an irregular alternating “big/little buzz” mode is observed in the early stage of the large oscillation stage. Notably, the mildly throttled state exhibits three intriguing hysteresis properties compared to the unthrottled and higher throttled states. Firstly, hysteresis is observed in the shock train motion stage in the duct before unstart, along with the corresponding inverse process. Subsequently, hysteresis is noted in the unstart and restart of the high-speed duct, with a smaller hysteresis interval than in the unthrottled state. Finally, the hysteresis characteristics of oscillation mode switching and the corresponding inverse process are explored. Based on the analysis, the first two hysteresis phenomena are associated with the formation and dissipation of the separation bubble. The significant adverse pressure gradient constrains the cross-sectional capacity of the channel, rendering the disappearance of the separation bubble more challenging. The hysteresis in oscillation mode switching is linked to not only the channel cross-sectional capacity but also the state of the incoming boundary layer.

Swirl-induced hysteresis in a sudden expansion flow

Swirling sudden expansion flows are complex flow fields containing several coherent structures that depend on the swirl number and can exhibit hysteresis behavior between increasing and subsequently decreasing swirl levels. While these flows have extensively been studied in simple geometries, results involving special designed nozzles are scarce. Therefore, this paper aims to provide insights into a more complex geometry, specifically a two-step conical expansion with a converging outlet. Experimental data is acquired for changing swirl numbers at a Reynolds number in the range of 35, 000. Stereoscopic Particle Image Velocimetry is employed to characterize downstream flow structures, while Laser Doppler Velocimetry is used to characterize upstream structures and to determine the inlet swirl number. Several distinct flow patterns are found as a function of the swirl number and the identified flow patterns include, in order of increasing swirl, a Closed Jet Flow, an Open Jet Flow (OJF), and a Coandã Jet Flow (CoJF). A central positive axial velocity is noted for both OJF and CoJF downstream of the expansion due to the converging outlet geometry. At higher swirl numbers, Vortex Breakdown moves upstream into the nozzle until a negative axial velocity is noted in the inlet tube. For these higher swirl numbers, no hysteresis is observed in the inlet tube between increasing and subsequently decreasing swirl. However, downstream of the nozzle, it is observed that the CoJF detaches at a lower swirl number than the swirl number required for attachment, indicating a hysteresis effect between in- and decreasing swirl.

Effects of tributary inflows on unsteady flow hysteresis and hydrodynamics in the mainstream

ABSTRACT Flooding propagation is a crucial aspect of hydrological monitoring and forecasting. Previous studies have focused on hysteresis in the rating curve, caused by energy loss during flood propagation. However, the impact of tributary inflow on hysteresis downstream remains unclear, leading to inconsistent field observations on whether it strengthens or weakens hysteresis. In this study, we conducted flume experiments to identify the relationship between hysteresis in unsteady flow and the discharge magnitude of the tributary and the unsteady flow period in the mainstream. It was found that the discharge variations in the tributary had a larger influence on hysteresis compared to the periodical variations in the mainstream unsteady flow. Interestingly, the hysteresis of the unsteady flow had an initial strengthening followed by weakening as the tributary discharge increased. When the tributary inflow was low, the widening of the downstream cross-section sharpened the flood wave, increasing the hysteresis. However, as the tributary discharge increased to generate a backwater effect on the mainstream, the pressure gradient flattened flood waves, thereby weakening the hysteresis. This study improves our understanding of how tributary inflow affects flood propagation in the mainstream, offering new insights for flood prediction and control.

Hysteresis and ribbons in Taylor-Couette flow of a semidilute noncolloidal suspension

Hysteresis and ribbons in Taylor-Couette flow of a semidilute noncolloidal suspension

Seasonal increase in hydrological connectivity causes changing concentration–flow hysteresis patterns in headwaters of high mountain catchments

ABSTRACT We studied seasonal differences in the hydrological connectivity between a stream and the different hydrological compartments of a high mountain catchment, analyzing the hysteresis patterns during storm events. Stream water was sampled with autosamplers to capture an entire rainfall event at 2 sites at different altitudes during the snow-free season. Stream solute concentration (C) – discharge (Q) hysteresis patterns changed over the season, in parallel with indicators of the hydrological connectivity in the catchment. We present a numerical model based on 3 end-members (atmospheric water and shallow and deep groundwater) to reproduce the observed changes in hysteresis by simulating stages with increased connectivity. The hydrological connectivity of the catchment increased with precipitation, dependent on the level of recharge of the non-surface compartments. Our results highlight the importance of groundwater in forming streamflow in high mountain catchments and how connectivity influences solute transport pathways.

Direct pore-scale simulation of the effect of capillary number and gas compressibility on cyclic underground hydrogen storage & production in heterogeneous aquifers

Understanding the flow dynamics of hydrogen-water in aquifers is critical to maximizing hydrogen storage and recovery. By using direct computational fluid dynamics at elevated pressure, this paper aims at detailed pore-scale investigation of the effect of flow regime, compressibility, and hysteresis on flow pattern, trapping mechanisms and the efficiency of hydrogen storage and recovery. The results reveal that the favorable rates during hydrogen injection and production differ and a medium flow rate corresponding to drainage capillary number of ∼10−7 and imbibition capillary number of ∼10−5 can minimize both capillary and viscous fingering mechanisms, leading to more storability and recovery factor. We show that neglecting the local compression and expansion of hydrogen and a low working pressure, typical in modeling and experimental studies, result in misinterpretation of flow regimes and hydrogen storability. Finally, we report that during the cyclic process, the trapped hydrogen bubbles produce a “self-cushion gas" effect, improving hydrogen storage.

Pores collapse hysteresis damage evaluation in depletion-dependent oil reservoirs using an asymptotic-integro-differential perturbation method

This work proposes a new asymptotic-perturbative solution for transient pores collapse hysteresis modeling in depletion-dependent oil reservoirs with compaction effects during alternating loading/unloading cycles. The nonlinear hydraulic diffusivity equation (NHDE) is perturbed through a first-order expansion technique using the depletion-dependent permeability, k(p) as a perturbation parameter, ϵ. A new hysteretic deviation factor is presented for flow (drawdown) and well-shut (buildup) periods. This factor represents the permeability deviation during the drawdown and its partial restoration in the buildup period. The model calibration is performed by a porous media numerical oil flow simulator named IMEX®, and the results presented high accuracy for the drawdown and buildup of hysteretic and non-hysteretic cases (when the pores collapse did not occur yet). The practical uses of the model developed in this work are related to identifying flow regimes and hysteresis responses in pressure-sensitive reservoirs, estimating buildup pressure, and oil flow rates specification to prevent severe hysteretic behavior and history matching during reservoir surveillance. Two case studies related to different reservoir layers are researched, and for both cases, the results from the log–log plots analysis have shown that the infinite-acting-radial oil flow (1/2 value of the slope of the pseudo-pressure derivative) was identified. In addition, the log–log analysis also shows that the shut-in pressure has an influence on permeability loss. The main advantages of the solution derived in this work are the simple implementation, practical graphical analysis of the pores collapse hysteresis effect, the possibility of simulating different boundary conditions and well-reservoir settings, and the requirements of only a few pressure and permeability field data to input in the deviation factor. The solution proposed can be applied to choose the production time to shut the well and monitor the adequate oil flow rate during the production curve.

Numerical investigation on expansion–deflection nozzle flow during an ascending–descending trajectory

The flow characteristics of an annular expansion–deflection (ED) nozzle are investigated numerically during an ascending–descending trajectory over a large nozzle pressure ratio span. The shock pattern evolution, nozzle operation mode transition, nozzle flow hysteresis, and thrust variation during this trajectory are examined, and the interactions between them are discussed. A new criterion for distinguishing the open and closed wake modes of the ED nozzle is proposed based on a perturbation front in combination with sonic lines. Using this criterion, an exact boundary between the open and closed wake modes can be readily drawn. The present study shows that the interaction between the shock pattern transition and nozzle operation mode transition is indirect. During the ascent, the open-to-closed wake mode transition lays the foundation of the downstream shock pattern variation. During the descent, however, the stretching of the dominating Mach stem delays the nozzle closed-to-open wake mode transition. The different flow mechanisms during the ascent and descent result in an overall hysteresis of nozzle operation mode transition. The nozzle thrust undergoes dropping-rising developments (the thrust troughs) in the ascent and descent. These thrust troughs are also found to be the results of two very different flow mechanisms, namely, the forward–backward movement of shock separation point on nozzle shroud and the pressure rise on pintle base after closed-to-open mode transition.

Characteristics of cavitation evolution through a butterfly valve under transient regulation

As the key control equipment for the transmission of the fluid medium, butterfly valves are widely used in transmission systems of media in the energy, chemical industry, metallurgy, aerospace engineering, and other fields, playing an important role in the stability and reliability of system operation. When the flow cross section suddenly changes, the pressure rapidly decreases the downstream, leading to cavitation in butterfly valves. Cavitation causes serious erosion and damage in the valve core and pipeline surface, resulting in leakage and noise problems in butterfly valves, which seriously affects the regulation performance and lifetime of butterfly valves. In this study, numerical analyses are conducted to investigate cavitation evolution at the transient regulation of a butterfly plate through a butterfly valve model. Moreover, the effects of the valve opening degree and rotating speed on the cavitation volume and distribution, rate of cavitation volume change, growth–collapse rate of cavitation, and correlation between cavitation and vortex in the opening and closing processes of butterfly valves are investigated. Due to the influence of transient regulation and flow hysteresis, the characteristic parameters and evolution of cavitation exhibit different behaviors in the opening and closing processes of butterfly valves.

Metal flow hysteresis behavior and shape control strategy during porthole die extrusion of micro heat pipe

The shape control strategy of micro grooves is still unclear and challenging during the porthole die extrusion of grooved micro heat pipe (MHP). Through the simulation and experiment of porthole die extrusion of a MHP profile, the metal flow hysteresis behavior within micro features and the effect of ram speed and extrusion temperature on it and the resulting forming integrity was elucidated. Innovatively, Taguchi design and variance analysis (ANOVA) were introduced to determine their influence magnitude on the metal flow uniformity calculated by simulation results. The main findings are given below. The metal flow hysteresis derives from part feature size effect. The negligible friction-affected area during conventional extrusion severely slows down the metal flow within micro features during the MHP profile extrusion, which is due to the surge in the area ratio of the friction-affected area to the region in which it is located. Neither ram speed nor extrusion temperature can change the distribution of the friction-affected area. However, increasing ram speed multiplies the metal flow hysteresis and severely reduces the forming integrity, whereas extrusion temperature has little effect. Following this strategy, batch extrusion of the profile with micro-grooved width of 0.27 ± 0.02 mm was achieved in industrialized conditions.

Mechanism analysis of hysteretic aerodynamic characteristics on variable-sweep wings

Variable-sweep wings have large shape-changing capabilities and wide flight envelops, which are considered as one of the most promising directions for intelligent morphing UAVs. Aerodynamic investigations always focus on several static states in the varying sweep process, which ignore the unsteady aerodynamic characteristics. However, deviations to static aerodynamic forces are inevitably caused by dynamic sweep motion. In this work, first, unsteady aerodynamic characteristics on a typical variable-sweep UAV with large aspect ratio were analyzed. Then, deep mechanism of unsteady aerodynamic characteristics in the varying sweep process was studied. Finally, numerical simulation method integrated with structured moving overset grids was applied to solve the unsteady fluid of varying sweep process. The simulation results of a sweep forward-backward circle show a distinct dynamic hysteresis loop surrounding the static data for the aerodynamic forces. Compared with the static lift coefficients , at the same sweep angles, dynamic lift coefficient in sweep forward process are all smaller, while dynamic sweep backward lift coefficient are all larger. In addition, dynamic deviations to static lift coefficient are positively related with the varying sweep speeds. Mechanism study on the unsteady aerodynamic characteristics indicates that three key factors lead to the dynamic hysteresis loop in varying sweep process. They are the effects of additional velocity caused by varying sweep motion, the effects of flow hysteresis and viscosity. The additional velocity induced by sweep motion affects the transversal flow direction along the wing and the effective angle of attack at the airfoil profile. The physical properties of flow, the hysteresis and viscosity affect the unsteady aerodynamic characteristics by flow separation and induced vortexes.

Instabilities of Transonic Turbulent Flow over a Flat-Sided Wedge

The transonic turbulent two-dimensional airflow over a symmetric flat-sided double wedge is studied numerically. Solutions of the Reynolds-averaged Navier-Stokes equations are obtained with ANSYS-18.2 CFX finite-volume solver of second order accuracy on a fine mesh. The solutions demonstrate an extreme sensitivity of the flow field and lift coefficient to variation of the angle of attack α or free-stream Mach number M∞. Non-unique flow regimes and hysteresis in certain bands of α and M∞ are identified. Interaction of shock waves and local supersonic regions is discussed. The study confirms a concept of shock wave instability due to a coalescence/rupture of supersonic regions. In addition to the instability of shock wave locations, the numerical simulation shows a buffet onset, i.e., self-exciting oscillations due to instability of a boundary layer separation at the rear of wedge. Curious flow regimes with positive lift at negative angles α and, vice versa, with negative lift at positive angles α, are pointed out. A piecewise continuous dependence of the lift coefficient on two free-stream parameters, α and M∞, is discussed.

Numerička analiza tegljajućeg nadzvučnog dvokrilca u uslovima van projektovanja sa zaklopkom zadnje ivice

Supersonic biplanes can achieve low-boom and low-drag supersonic flights. In the present study, aerodynamic analysis of a two-dimensional stagger Bussmann biplane (staggered upper element by 0.5c) at zero degrees angle of attack with trailing edge flap was investigated with the help of computational fluid dynamics (CFD) tools. Due to the wave cancellation effect, the Busemann biplane delivers a positive drag reduction at design supersonic Mach values. However, when operating outside of its intended parameters, it performs worse, and the wave cancellation effect has no beneficial effects on reducing drag. Another issue with the Busemann biplane is flow chocking, which produces a potent bow shock wave in front of the aircraft. This paper attempts to address low aerodynamics efficiency problems during take-off through numerical simulation of a staggered Busemann biplane with trailing edge flaps at zero degrees angle of attack. It was confirmed that the staggered biplane airfoil with flap has better aerodynamic performance during take-off at lower subsonic free stream Mach numbers. In 2D wings, the effect of flow chocking and hysteresis as starting problems, which arise when the biplanes accelerate from low Mach numbers, is reduced by using the suitable dimension and angle of rotation of the flap, and the flap is effective in settling these issues.

Diffusive wave models for operational forecasting of channel routing at continental scale

AbstractOperational forecast models require robust, computationally efficient, and reliable algorithms. We desire accurate forecasts within the limits of the uncertainties in channel geometry and roughness because the output from these algorithms leads to flood warnings and a variety of water management decisions. The current operational Water Model uses the Muskingum‐Cunge method, which does not account for key hydraulic conditions such as flow hysteresis and backwater effects, limiting its ability in situations with pronounced backwater effects. This situation most commonly occurs in low‐gradient rivers, near confluences and channel constrictions, coastal regions where the combined actions of tides, storm surges, and wind can cause adverse flow. These situations necessitate a more rigorous flow routing approach such as dynamic or diffusive wave approximation to simulate flow hydraulics accurately. Avoiding the dynamic wave routing due to its extreme computational cost, this work presents two diffusive wave approaches to simulate flow routing in a complex river network. This study reports a comparison of two different diffusive wave models that both use a finite difference solution solved using an implicit Crank–Nicolson (CN) scheme with second‐order accuracy in both time and space. The first model applies the CN scheme over three spatial nodes and is referred to as Crank–Nicolson over Space (CNS). The second model uses the CN scheme over three temporal nodes and is referred to as Crank–Nicolson over Time (CNT). Both models can properly account for complex cross‐section geometry and variable computational points spacing along the channel length. The models were tested in different watersheds representing a mixture of steep and flat topographies. Comparing model outputs against observations of discharges and water levels indicated that the models accurately predict the peak discharge, peak water level, and flooding duration. Both models are accurate and computationally stable over a broad range of hydraulic regimes. The CNS model is dependent on the Courant criteria, making it less computational efficient where short channel segments are present. The CNT model does not suffer from that constraint and is, thus, highly computationally efficient and could be more useful for operational forecast models.

Experimental study on effect of magnetic field on flow dynamics of iron (III) oxide (Fe2O3) - water based nanofluid using Taylor Couette flow apparatus

Experimental investigation of magnetic field effect on Fe3O4-Water based nanofluid undergoing Taylor Couette flow is of great importance since some lubricating systems are replicas of Taylor Couette flow. In this study several experiments were carried out to investigate the influence of nanoparticle concentration on the vortex dynamics of a water based Newtonian nanofluid formulated from Fe2O3 in the presence and absence of magnetic field. Flow dynamics was studied in relation to flow transition, stability, hysteresis and effect of magnetism on these properties. Flow regimes covered in this study include Circular Couette flow, Taylor vortex flow, wavy Vortex flow and Modulated Wavy vortex flow. Bifurcation parameters are nanoparticle volume fraction, inner cylinder rotating frequency and Reynolds number. Experiments were performed on distilled water and Fe3O4-Water based nanofluid to understand its behavior in Taylor Couette apparatus. Critical Reynolds number, Azimuthal wavenumber and travelling waves frequency was recorded for each nanoparticle volume fraction. Power Spectral Analysis of nanofluid flow was carried out using video data from the experiment. It was observed that critical frequency for various transitions decrease with nanoparticle volume fraction for nanofluid in the presence of magnetic field but an inconsistent pattern was observed for nanofluid in the absence of magnetic field. These results show that magnetic field and nanoparticle volume fraction greatly influence the behavior of the flow.

Computational fluid dynamic simulation of multi-phase flow in fractured porous media during water-alternating-gas injection process

Naturally fractured reservoirs (NFRs) are among major oil and gas producing reservoirs that are commonly targeted for various enhanced oil recovery (EOR) techniques, particularly water-alternating-gas (WAG) injection. Production from NFRs is complicated due to the flow communication between the matrix and fractures in such porous media. The implementation of WAG injection in NFRs features inherent complexities not only related to the three-phase flow, saturation history, and cycle-dependent hysteresis of the individual phases, but also the fracture-matrix communication, fingering, and early breakthrough of the injected phases particularly during gas injection processes. This paper provides the key results on the computational fluid dynamics (CFD) simulation of WAG injection in a fractured system. We evaluate the impacts of hysteresis, fracture characteristics (aperture, orientation, and fracture density in the network), and the three-phase relative permeability of available phases during the WAG injection. The CFD model simulates an immiscible WAG injection, and the CFD results are compared to the experimental data in a strongly water-wet sand-pack. Similar to the experiments, we simulate Maroon crude as the oil phase, and synthetic brine, and pure CO2 at 100 °C and atmospheric outlet pressure. The CFD results are in excellent agreement with the experimental data. The absolute relative error is less than 12% for predicting the ultimate oil recovery factors (RFs) in water flooding (WF) and gas injection (GI) cycles. Including the three-phase hysteresis significantly increases the accuracy of the WAG process simulation, while excluding hysteresis underestimates the instantaneous RFs at each cycle (especially GI cycles) and the ultimate RF by 4%. We also analyze the fracture pattern and configuration; adding fractures to the system increases the system effective permeability, leading to more contact between the injecting fluid and trapped oil, and consequently higher oil recovery. Connecting a vertical fracture to the horizontal fracture enhances the recovery through strong connections between the vertical and horizontal blocks. An increase in the fracture aperture from 0.5 to 3 mm increases the RF from 50% to 59%. The fracture inclination angle from 30° to 90° increases the ultimate RF by only 2%. Including gravity forces in vertical model orientation results in overall improvement in RF through engaging both matrix and fracture media in all cycles. As the permeability contrast between the matrix and fracture media decreases, the flow communication between the two regions increases, which improves the recovery performance of the WAG process. Our simulation results can help to further understand the effect of various parameters and operational conditions on WAG injection performance in fractured reservoirs.

Elucidating the role of network topology dynamics on the coil-stretch transition hysteresis in extensional flow of entangled polymer melts

Dissipative particle dynamics (DPD) simulations are performed on coarse-grained replicas of linear, monodisperse entangled polyethylene melts C1000H2002 and C3000H6002 undergoing both steady-state and transient planar elongational flow (PEF). The fidelity of the DPD simulations is verified by direct comparison of flow topological and rheological properties of a 334-particle chain liquid against the united-atom C1000H2002 liquid, simulated using nonequilibrium molecular dynamics (NEMD). These DPD simulations demonstrate that a flow-induced coil-stretch transition (CST) and its associated hysteresis caused by configurational microphase separation, as observed in previous NEMD simulations of PEF, can be replicated using a more computationally efficient coarse-grained system. Results indicate that the breadth of the CST hysteresis loop is enlarged for the longer molecule liquid relative to the shorter one. Furthermore, relaxation simulations reveal that reducing the applied flow Deborah number (De) from a high value corresponding to a homogeneous phase of highly stretched molecules to a De within the biphasic region results in a two-stage relaxation process. There is a fast initial stratification of the kinetically trapped highly stretched chains into regions of highly extended and less extended chains, which displays similar behavior to a system undergoing a spinodal decomposition caused by spatial configurational free energy fluctuations. After a short induction period of apparently random duration, the less extended chain regions experience a stochastic nucleation event that induces configurational relaxation to domains composed of coiled molecules over a much longer time scale, leaving the more highly extended chains in surrounding sheetlike domains. The time scales of these two relaxation processes are of the same order of magnitude as the Rouse and disengagement times of the equilibrium liquids.

Hysteresis in a two-liquid whirlpool

This experimental study reveals a curious phenomenon—hysteresis in a lab-scale two-liquid flow. The rotating bottom disk drives a toroidal circulation of water–glycerin solution (lower fluid) and sunflower oil (upper fluid) in a vertical cylindrical container. As the rotation speeds up, the solution–oil interface and the oil–air (free) surface deform rising near the sidewall and depressing near the axis as typical of whirlpools. We choose that the oil–solution volume ratio be small (having in mined oil-pollution applications) but not too small (for convenient observation). As the rotation speeds up, the oil separates from the sidewall and collects in the solution funnel. Next, the interface touches the bottom, and this is the point of no return. The centrifugal force pushes the near-bottom oil to the periphery and the buoyancy pushes oil upward. The Rayleigh–Taylor instability breaks the interface, and oil droplets disperse in the solution. If before this breakdown, the rotation starts to decrease, the oil separates from the bottom at the angular velocity ω being remarkably smaller than that for which the oil touches the bottom. Therefore, the hysteresis is a capillary-induced phenomenon.

Thixotropy and rheological hysteresis in blood flow.

Hemorheology is known to be a major diagnostic tool for many blood-altering diseases. While hemorheological measures of blood, such as the general flow curve, shear-thinning behavior, and its yield stress, are much more studied in detail, thixotropic behavior and thermokinematic memory formation in blood are less understood. Here, we study the thermokinematic memory formation in blood, resulting in a clear sensitivity to the flow history, i.e., thixotropic behavior. We also measure the thixotropic timescale for blood flow using a well-defined flow protocol. Employing a series of in silico flow loops in which the blood is subject to a sweep down/up flow, we measure and discuss the dependence of the thixotropic timescale to the concentration of fibrinogen in the plasma as the main driver of structural evolution under flow.

Novel predictors related to hysteresis and baseflow improve predictions of watershed nutrient loads: An example from Ontario's lower Great Lakes basin

Eutrophication has re-emerged in the lower Great Lakes basin resulting in critical water quality issues. Models that accurately predict nutrient loading from streams are needed to inform appropriate nutrient management decisions. Generalized additive models (GAMs) that use surrogate data from sensors to predict nutrient loads offer an alternative to commonly applied linear regression and may better handle relationship non-linearities and skewed water quality data. Five years (2015–2020) of water quantity and quality data from 11 agricultural watersheds in southern Ontario were used to develop GAMs to predict total phosphorus (TP) and nitrate (NO3−) loads. This study aimed to 1) use GAMs to predict nutrient loads using both common and novel predictors and 2) quantify and examine the variability in seasonal and annual nutrient loads. Along with routine surrogate model predictors (i.e., flow, turbidity, and seasonality), the addition of the baseflow proportion and the hydrograph position of flow observations improved model performance. Conversely, including the antecedent precipitation index minimally affected model performance, regardless of constituent. Seasonal and annual patterns in TP and NO3− load predictions mirrored that of the hydrologic regime. This study showed that parsimonious GAMs featuring novel model predictors can be used to predict nutrient loads while accounting for the partitioning of surface and subsurface flow paths and hysteresis between streamflow and water quality parameters that are frequently observed in a wide range of environments.