Mauro Rodriguez

Brown University · Brown School of Engineering

Accurate determination of high strain rate (> 10 3 1/s) constitutive properties of soft materials remains a formidable challenge. Albeit recent advancements among experimental techniques, in particular inertial microcavitation rheometry (IMR), the intrinsic requirement to visualize the bubble cavitation dynamics has limited its application to nomin...

Multiphase compressible flows are often characterized by a broad range of space and time scales. Thus entailing large grids and small time steps, simulations of these flows on CPU-based clusters can thus take several wall-clock days. Offloading the compute kernels to GPUs appears attractive but is memory-bound for standard finite-volume and -differ...

A numerical model for cavitation in blood is developed based on the Keller–Miksis equation for spherical bubble dynamics with the Carreau model to represent the non-Newtonian behavior of blood. Three different pressure waveforms driving the bubble oscillations are considered: a single-cycle Gaussian waveform causing free growth and collapse, a sinu...

The collapse of cavitation bubbles in channel flows can give rise to structural damage along neighbouring walls. Although the collapse of a bubble near a single wall has been studied extensively, less is known about bubble collapse between two walls, e.g. as in a channel. We conduct highly resolved, direct simulations of the Navier–Stokes equations...

No PDF available ABSTRACT Understanding the interaction of acoustic waves and stones is of principal importance to the development and optimization of shock wave and ultrasound-based therapies, such as shock wave and burst wave lithotripsy (SWL and BWL). Simulating these interactions is useful in furthering our understanding, but the development of...

Biomedical therapies use focused ultrasound to treat pathogenic tissues. The ultrasound waves lead to nucleation, grow and collapse of bubbles. Previous numerical simulations of this process have treated the bubble contents as non-condensible gas, but it is known that phase change affects the bubble dynamics as a function of the driving frequency a...

Burst-wave lithotripsy (BWL) is a therapy for ablating kidney and gall bladder stones. During therapy, high-amplitude ultrasound waves issue from a transducer array and focus near the stone. These waves can nucleate clouds of small bubbles at the surface of the stone. This can affect treatment efficacy: acoustic shielding due to the bubble clouds c...

Understanding the impact load mechanisms from cavitation bubbles and shocks emitted by their collapse in and near solid deformable media is important for engineering and biomedical applications. In such flows, transient pressure fluctuations can lead to a cloud of small vapor bubbles near the solid object. A unified Eulerian framework for fluid-str...

An understanding of the acoustic cavitation threshold is essential for minimizing cavitation bio-effects in diagnostic ultrasound and for controlling cavitation-mediated tissue ablation in focused ultrasound procedures. The homogeneous cavitation threshold is an intrinsic material property of recognized importance to biomedical ultrasound as well a...

A variety of approaches have been used to model the dynamics of a single, isolated bubble nucleated by a microsecond length high–amplitude ultrasound pulse (e.g. a histotripsy pulse). Until recently, the lack of single–bubble experimental radius vs. time data for bubble dynamics under a well–characterized driving pressure has limited model validati...

Viscoelastic material properties at high strain rates are needed to model many biological and medical systems. Bubble cavitation can induce such strain rates, and the resulting bubble dynamics are sensitive to the material properties. Thus, in principle, these properties can be inferred via measurements of the bubble dynamics. Estrada et al. (2018)...

Viscoelastic material properties at high strain rates are needed to model many biological and medical systems. Bubble cavitation can induce such strain rates, and the resulting bubble dynamics are sensitive to the material properties. Thus, in principle, these properties can be inferred via measurements of the bubble dynamics. Estrada et al. (2018)...

A variety of approaches have been used to model the dynamics of a single, isolated bubble nucleated by a microsecond length high-amplitude ultrasound pulse (e.g., a histotripsy pulse). Until recently, the lack of single--bubble experimental radius vs. time data for bubble dynamics under a well-characterized driving pressure has limited model valida...

Understanding the acoustic cavitation threshold is essential for minimizing cavitation bioeffects in diagnostic ultrasound and for controlling cavitation--mediated tissue ablation in focused ultrasound procedures. The homogeneous cavitation threshold is an intrinsic material property of recognized importance to a variety of applications requiring c...

The destructive growth and collapse of cavitation bubbles are used for therapeutic purposes in focused ultrasound procedures and can contribute to tissue damage in traumatic injuries. Histotripsy is a focused ultrasound procedure that relies on controlled cavitation to homogenize soft tissue. Experimental studies of histotripsy cavitation have show...

Experimental observations of the growth and collapse of acoustically and laser-nucleated single bubbles in water and agarose gels of varying stiffness are presented. The maximum radii of generated bubbles decreased as the stiffness of the media increased for both nucleation modalities, but the maximum radii of laser-nucleated bubbles decreased more...

No PDF available ABSTRACT Here, we present results from experiments comparing the first-cycle growth and collapse dynamics of acoustically and laser-nucleated single bubbles in water and agarose gels of varying stiffness. Experiments were carried out in a custom-built spherical vessel which allowed both acoustically and laser-nucleated bubbles to b...

A novel Eulerian approach is proposed for numerical simulations of wave propagation in viscoelastic media, for application to shocks interacting with interfaces between fluids and solids. We extend the five-equations multiphase interface-capturing model, based on the idea that all the materials (gases, liquids, solids) obey the same equation of sta...

An Eulerian approach for simulations of wave propagation in multiphase, viscoelastic media is developed in the context of the Advection Upstream Splitting Method (AUSM). We extend the AUSM scheme to the five-equation model for simulations of interfaces between gases, liquids, and solids with constitutive relations appropriately transported. In this...